Secrets, spy tools and a 110-year-old lemon are on show in an exhibition from Britain's MI5

LONDON (AP) — A desiccated 110-year-old lemon that played a key role in espionage history is one of the star attractions of a London exhibition drawn from the files of MI5, Britain’s domestic intelligence agency.

Compact spy cameras, microdots in a talcum powder tin and a briefcase abandoned by fleeing Soviet spy Guy Burgess are also part of the show at Britain’s National Archives, which charts the history of a secretive agency that is – slowly – becoming more open.

MI5 Director General Ken McCallum told journalists at a preview on Tuesday that the organization’s work “is often different from fiction, whether that fiction is George Smiley or Jackson Lamb” – the brilliant spymaster of John le Carré's novels and the slovenly supervisor of MI5 rejects in Mick Herron’s “Slow Horses” series.

Many stories told in the exhibition, however, would not be out of place in a thriller.

The lemon, now black and shriveled, helped convict Karl Muller, a German spy in Britain during World War I. It was found by police in his dressing-table drawer, along with another in his overcoat pocket. Evidence at his secret trial showed their juice had been used to write invisible-ink letters detailing British troop movements.

Muller was executed by firing squad at the Tower of London in 1915.

In a coda that would not be out of place in “Slow Horses,” MI5 pretended Muller was still alive and wrote to his German handlers to ask for more money.

“The Germans duly sent more funds and MI5 used the funds to purchase a car,” exhibition curator Mark Dunton said. “And they christened the car ‘The Muller.’

“They then were reprimanded by the Treasury for unauthorized use of expenditure," he added.

The show includes declassified records held by the National Archives and items loaned from the secret museum inside Thames House, MI5’s London headquarters.

It charts the changing role of an agency that was founded in 1909 as the Secret Service Bureau with an initial staff of two officers.

There are records of its World War II successes, when the agency used captured Nazi agents to send disinformation back to Germany, deceiving Adolf Hitler about the location of the looming Allied invasion in 1944.

Failures include the years-long betrayal of the upper-crust “Cambridge Spies,” whose members spilled secrets to the Soviet Union from the heart of the U.K. intelligence establishment. Recently declassified MI5 documents on display include the 1963 confession of Cambridge spy Kim Philby, who denied treachery for years before he was exposed and fled to Moscow.

The exhibition also reveals changing attitudes, not least to women. The exhibition includes a 1945 report by spymaster Maxwell Knight discussing whether women could make good agents.

“It is frequently alleged that women are less discreet than men,” he noted, but declared that it was not so, saying that in “hundreds of cases of ‘loose talk’” most of the offenders were men.

There are admissions of past mistakes. The exhibition notes that MI5 was slow to recognize the threat from fascism in the 1930s, and later spent too much time spying on the small Communist Party of Great Britain. MI5 didn’t need to break into the party’s offices – it had a key, which is on display.

There are only a few items from the past few decades, showing how MI5’s focus has shifted from counterespionage to counterterrorism. Displays include a mortar shell fired by the Irish Republican Army at 10 Downing St. in 1991 while Prime Minister John Major was holding a Cabinet meeting.

MI5 only began releasing records to the U.K.’s public archives in 1997, generally 50 years after the events have passed. Even now, it controls what to release and what to keep secret.

“It would be a mistake to assume everything is in the exhibition,” said author Ben Macintyre, whose books on the history of intelligence include “Operation Mincemeat” and “Agent Zigzag.” But he said it still marks “a real sea-change in official secrecy.”

“A generation ago, this stuff was totally secret,” he said. “We weren’t even allowed to know that MI5 existed.”

“MI5: Official Secrets” opens Saturday and runs through Sept. 28 at the National Archives in London. Admission is free.

A National Archives staff member looks at a 1910 Enseignette camera, the first spy camera purchased by MI5, during a preview for the MI5: Official Secrets exhibition at the National Archives in London, Tuesday, April 1, 2025. (Jonathan Brady/PA via AP)

A Yardley talcum powder tin from 1960 used by one of the Portland spies to conceal microdot equipment on display during a preview for the MI5: Official Secrets exhibition at the National Archives in London, Tuesday, April 1, 2025. (Jonathan Brady/PA via AP)

The Krogers' 'flash transmission' radio equipment, 1960, on display during a preview for the MI5: Official Secrets exhibition at the National Archives in London, Tuesday, April 1, 2025. (Jonathan Brady/PA via AP)

The lemon used for writing in invisible ink, produced in evidence at Karl Muller's trial, 1915, on display during a preview for the MI5: Official Secrets exhibition at the National Archives in London, Tuesday, April 1, 2025. (Jonathan Brady/PA via AP)

A copy of the German War Merit Cross 'Kriegsverdienstkreuz', 1939 on display during a preview for the MI5: Official Secrets exhibition at the National Archives in London, Tuesday, April 1, 2025. (Jonathan Brady/PA via AP)

MI5 staff list on display during a preview for the MI5: Official Secrets exhibition at the National Archives in London, Tuesday, April 1, 2025. (Jonathan Brady/PA via AP)

Director General of MI5, the UK's Security Service, Ken McCallum, during a preview for the MI5: Official Secrets exhibition at the National Archives in London, Tuesday, April 1, 2025. (Jonathan Brady/PA via AP)

A National Archives staff member looks at an example of an instant camera and bottle used to make a bomb, recreated as evidence by the Bomb Data Centre, on display during a preview for the MI5: Official Secrets exhibition at the National Archives in London, Tuesday, April 1, 2025. (Jonathan Brady/PA via AP)

Guy Burgess' passport on display during a preview for the MI5: Official Secrets exhibition at the National Archives in London, Tuesday, April 1, 2025. (Jonathan Brady/PA via AP)

EA National Archives member of staff looks at a Britain First report of Mosley's speech at Earl's Court, 16 July 1939, left, and a British Union of Fascists armband, right, during a preview for the MI5: Official Secrets exhibition at the National Archives in London, Tuesday, April 1, 2025. (Jonathan Brady/PA via AP)

National Archives staff members look at facets of a recreation of the double cross operation room which was headed up by the XX committee circa 1944, during a preview for the MI5: Official Secrets exhibition at the National Archives in London, Tuesday, April 1, 2025. (Jonathan Brady/PA via AP)

Director General of MI5, the UK's Security Service, Ken McCallum, during a preview for the MI5: Official Secrets exhibition at the National Archives in London, Tuesday, April 1, 2025. (Jonathan Brady/PA via AP)

National Archives staff members look at facets of a recreation of the double cross operation room which was headed up by the XX committee circa 1944, during a preview for the MI5: Official Secrets exhibition at the National Archives in London, Tuesday, April 1, 2025. (Jonathan Brady/PA via AP)

Guy Burgess' passport and briefcase on display during a preview for the MI5: Official Secrets exhibition at the National Archives in London, Tuesday, April 1, 2025. (Jonathan Brady/PA via AP)

National Archives staff members look at facets of a recreation of the double cross operation room which was headed up by the XX committee circa 1944, during a preview for the MI5: Official Secrets exhibition at the National Archives in London, Tuesday, April 1, 2025. (Jonathan Brady/PA via AP)

NEW YORK (AP) — U.S. stocks are careening through a manic Monday after President Donald Trump threatened to crank his tariffs higher, despite a stunning display from Wall Street showing how dearly it wants him to do the opposite.

The S&P 500 was down 0.8% in late trading, but only after a shocking day of heart-racing reversals as battered financial markets try to figure out what Trump’s ultimate goal is for his trade war. If it’s to get other countries to agree to trade deals, he could lower his tariffs and avoid a possible recession. But if it’s to remake the economy and stick with tariffs for the long haul, stock prices may need to fall further.

The Dow Jones Industrial Average was down 563 points, or 1.5%, with a little less than an hour remaining in trading, while the Nasdaq composite was 0.6% lower.

All three indexes started the day sharply lower, and the Dow plunged as many as 1,700 points following even worse losses worldwide on worries that Trump's tariffs could torpedo the global economy. But it suddenly surged to a gain of nearly 900 points. The S&P 500, meanwhile, went from a loss of 4.7% to a leap of 3.4%, which would have been its biggest jump in years.

The sudden rise followed a false rumor that Trump was considering a 90-day pause on his tariffs, one that a White House account on X quickly labeled as “fake news.” Stocks then turned back down. That a rumor could move trillions of dollars' worth of investments shows how much investors are hoping to see signs that Trump may let up on tariffs.

But soon after that, Trump threatened to raise tariffs further against China after the world's second-largest economy retaliated last week with its own set of tariffs on U.S. products.

It’s a slap in the face to Wall Street, not just because of the sharp losses it’s taking, but because it suggests Trump may not be moved by its pain. Many professional investors had long thought that a president who used to crow about records reached under his watch would pull back on policies if they sent the Dow reeling.

On Sunday Trump told reporters aboard Air Force One that he does not want markets to fall. But he also said he wasn’t concerned about a sell-off, saying “sometimes you have to take medicine to fix something.”

Trump has given several reasons for his stiff tariffs, including to bring manufacturing jobs back to the United States, which is a process that could take years. Trump on Sunday said he wanted to bring down the numbers for how much more the United States imports from other countries versus how much it sends to them.

Still, indexes kept swerving between losses and gains Monday, even after Trump threatened to raise his tariffs, because hope still remains in markets that negotiations may still come.

“Could things get worse? Of course they could," said Nate Thooft, a senior portfolio manager at Manulife Investment Management. “We’re not calling the all-clear at all, but when you have this type of volatility in the market, of course you're going to have back and forth” in markets not just day to day but also hour to hour.

“We’re all waiting for the next bit of information,” he said. “Literally a Truth Social tweet or an announcement of some sort about real negotiations could dramatically move this market. This is the world we live in right now.”

All that seems to be certain is that the financial pain hammered investments around the world on Monday, the third straight day of steep losses after Trump announced tariffs in his “Liberation Day.”

Stocks in Hong Kong plunged 13.2% for their worst day since 1997. A barrel of benchmark U.S. crude oil dipped below $60 during the morning for the first time since 2021, hurt by worries that a global economy weakened by trade barriers will burn less fuel. Bitcoin sank below $79,000, down from its record above $100,000 set in January, after holding steadier than other markets last week.

Nike dropped 4% for one of the larger losses on Wall Street. Not only does it sell a lot of shoes and apparel in China, it also makes much of it there. Last fiscal year, factories in China made 18% of its Nike brand footwear. Vietnam made 50%, and Indonesia made 27%.

Trump’s tariffs are an attack on the globalization that’s remade the world’s economy, which helped bring down prices for products on the shelves of U.S. stores but also caused production jobs to leave for other countries.

It also adds pressure on the Federal Reserve. Investors have become nearly conditioned to expect the central bank to swoop in as a hero by slashing interest rates during downturns.

But the Fed may have less freedom to act this time around because the conditions are so much different. That's cheifly because inflation is higher at the moment than the Fed would like. And while lower interest rates can goose the economy, they can also put upward pressure on inflation. Expectations for inflation are already swinging higher because of Trump’s tariffs, which would likely raise prices for anything imported.

“The recent tariffs will likely increase inflation and are causing many to consider a greater probability of a recession,” JPMorgan CEO Jamie Dimon, one of the most influential executives on Wall Street, wrote in his annual letter to shareholders Monday. “Whether or not the menu of tariffs causes a recession remains in question, but it will slow down growth.”

In the bond market, Treasury yields rallied Monday to recover some of their sharp drops from earlier weeks. Some of the big move may have been because of reduced expectations for cuts to interest rates by the Fed. Some analysts also said it could be due to investors outside of the United States wanting to pare their U.S. investments.

The yield on the 10-year Treasury jumped to 4.14% from 4.01% late Friday.

Earlier in the day, the S&P 500 briefly fell more than 20% below its record set less than two months ago. If it finishes a day below that bar, it would be a big enough drop that Wall Street has a name for it. A “bear market” signifies a downturn that’s moved beyond a run-of-the-mill 10% drop, which happens every year or so, and has graduated into something more vicious.

The S&P 500, which sits at the heart of many investors’ 401(k) accounts, is coming off its worst week since COVID began crashing the global economy in March 2020.

Kurtenbach reported from Bangkok. McHugh reported from Frankfurt, Germany. Associated Press writers Ayaka McGill, Paul Harloff, Matt Ott and Jiang Junzhe also contributed.

An electronic display shows financial information on the floor at the New York Stock Exchange in New York, Monday, April 7, 2025. (AP Photo/Seth Wenig)

Federico DeMarco works on the floor at the New York Stock Exchange in New York, Monday, April 7, 2025. (AP Photo/Seth Wenig)

Traders work on the floor at the New York Stock Exchange in New York, Monday, April 7, 2025. (AP Photo/Seth Wenig)

Chris Lagana works on the floor at the New York Stock Exchange in New York, Monday, April 7, 2025. (AP Photo/Seth Wenig)

Traders work on the floor at the New York Stock Exchange in New York, Monday, April 7, 2025. (AP Photo/Seth Wenig)

Traders work on the options floor at the New York Stock Exchange in New York, Monday, April 7, 2025. (AP Photo/Seth Wenig)

While a stock exchange trader sits in front of his monitors on the trading floor of the Frankfurt Stock Exchange, Germany, the display board with the Dax curve shows a value of less than 20,000 points. (Arne Dedert/dpa via AP)

While a stock exchange trader sits in front of his monitors on the trading floor of the Frankfurt Stock Exchange, Germany, the display board with the Dax curve shows a value of less than 20,000 points. (Arne Dedert/dpa via AP)

Currency traders work near a screen showing the Korea Composite Stock Price Index (KOSPI), top left, and the foreign exchange rate between U.S. dollar and South Korean won, top center, at the foreign exchange dealing room of the KEB Hana Bank headquarters in Seoul, South Korea, Monday, April 7, 2025. (AP Photo/Ahn Young-joon)

An electronic stock board shows that Nikkei stock average dropped over 2,900 Japanese yen in Tokyo Monday, April 7, 2025. (Kyodo News via AP)

Currency traders work near a screen showing the Korea Composite Stock Price Index (KOSPI) and the foreign exchange rate between U.S. dollar and South Korean won, top right, at the foreign exchange dealing room of the KEB Hana Bank headquarters in Seoul, South Korea, Monday, April 7, 2025. (AP Photo/Ahn Young-joon)

A person walks past an electronic stock board in Tokyo Monday, April 7, 2025. (Kyodo News via AP)

Currency traders watch monitors near a screen showing the Korea Composite Stock Price Index (KOSPI), top left, and the foreign exchange rate between U.S. dollar and South Korean won, top center, at the foreign exchange dealing room of the KEB Hana Bank headquarters in Seoul, South Korea, Monday, April 7, 2025. (AP Photo/Ahn Young-joon)

US President Donald Trump appears on a television screen at the stock market in Frankfurt, Germany, Thursday, April 3, 2025. (AP Photo/Michael Probst)

A screen displays financial news as traders work on the floor at the New York Stock Exchange in New York, Thursday, April 3, 2025. (AP Photo/Seth Wenig)