Secrets, Spy Tools and a 110-Year-Old Lemon Are on Show in an Exhibition from Britain’s MI5  

01 April 2025, United Kingdom, Richmond: Guy Burgess' passport and briefcase are displayed during a preview of the MI5: Official Secrets exhibition at the National Archives in Kew. (Jonathan Brady/PA Wire/dpa)
01 April 2025, United Kingdom, Richmond: Guy Burgess' passport and briefcase are displayed during a preview of the MI5: Official Secrets exhibition at the National Archives in Kew. (Jonathan Brady/PA Wire/dpa)
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Secrets, Spy Tools and a 110-Year-Old Lemon Are on Show in an Exhibition from Britain’s MI5  

01 April 2025, United Kingdom, Richmond: Guy Burgess' passport and briefcase are displayed during a preview of the MI5: Official Secrets exhibition at the National Archives in Kew. (Jonathan Brady/PA Wire/dpa)
01 April 2025, United Kingdom, Richmond: Guy Burgess' passport and briefcase are displayed during a preview of the MI5: Official Secrets exhibition at the National Archives in Kew. (Jonathan Brady/PA Wire/dpa)

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 bedside table, 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 UK 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 UK’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.”



Hungary's Oldest Library is Fighting to Save Books from Beetle Infestation

Books are kept in hermetically sealed plastic sacks for disinfection at the Pannonhalma Archabbey's library in Pannonhalma, Hungary, Thursday, July 3, 2025, as a beetle infestation threatens its ancient collection. (AP Photo/Bela Szandelszky)
Books are kept in hermetically sealed plastic sacks for disinfection at the Pannonhalma Archabbey's library in Pannonhalma, Hungary, Thursday, July 3, 2025, as a beetle infestation threatens its ancient collection. (AP Photo/Bela Szandelszky)
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Hungary's Oldest Library is Fighting to Save Books from Beetle Infestation

Books are kept in hermetically sealed plastic sacks for disinfection at the Pannonhalma Archabbey's library in Pannonhalma, Hungary, Thursday, July 3, 2025, as a beetle infestation threatens its ancient collection. (AP Photo/Bela Szandelszky)
Books are kept in hermetically sealed plastic sacks for disinfection at the Pannonhalma Archabbey's library in Pannonhalma, Hungary, Thursday, July 3, 2025, as a beetle infestation threatens its ancient collection. (AP Photo/Bela Szandelszky)

Tens of thousands of centuries-old books are being pulled from the shelves of a medieval abbey in Hungary in an effort to save them from a beetle infestation that could wipe out centuries of history.

The 1,000-year-old Pannonhalma Archabbey is a sprawling Benedictine monastery that is one of Hungary's oldest centers of learning and a UNESCO World Heritage site.

Restoration workers are removing about 100,000 handbound books from their shelves and carefully placing them in crates, the start of a disinfection process that aims to kill the tiny beetles burrowed into them, The Associated Press reported.

The drugstore beetle, also known as the bread beetle, is often found among dried foodstuffs like grains, flour and spices. But they also are attracted to the gelatin and starch-based adhesives found in books.

They have been found in a section of the library housing around a quarter of the abbey's 400,000 volumes.

“This is an advanced insect infestation which has been detected in several parts of the library, so the entire collection is classified as infected and must be treated all at the same time,” said Zsófia Edit Hajdu, the chief restorer on the project. “We've never encountered such a degree of infection before.”

The beetle invasion was first detected during a routine library cleaning.

Employees noticed unusual layers of dust on the shelves and then saw that holes had been burrowed into some of the book spines. Upon opening the volumes, burrow holes could be seen in the paper where the beetles chewed through.

The abbey at Pannonhalma was founded in 996, four years before the establishment of the Kingdom of Hungary. Sitting upon a tall hill in northwestern Hungary, the abbey houses the country's oldest collection of books, as well as many of its earliest and most important written records.

For over 1,000 years, the abbey has been among the most prominent religious and cultural sites in Hungary and all of Central Europe, surviving centuries of wars and foreign incursions such as the Ottoman invasion and occupation of Hungary in the 16th century.

Ilona Ásványi, director of the Pannonhalma Archabbey library, said she is “humbled” by the historical and cultural treasures the collection holds whenever she enters.

“It is dizzying to think that there was a library here a thousand years ago, and that we are the keepers of the first book catalogue in Hungary,” she said.

Among the library’s most outstanding works are 19 codices, including a complete Bible from the 13th century. It also houses several hundred manuscripts predating the invention of the printing press in the mid-15th century and tens of thousands of books from the 16th century.

While the oldest and rarest prints and books are stored separately and have not been infected, Ásványi said any damage to the collection represents a blow to cultural, historical and religious heritage.

“When I see a book chewed up by a beetle or infected in any other way, I feel that no matter how many copies are published and how replaceable the book is, a piece of culture has been lost,” she said.

To kill the beetles, the crates of books are being placed into tall, hermetically sealed plastic sacks from which all oxygen is removed. After six weeks in the pure nitrogen environment, the abbey hopes all the beetles will be destroyed.

Before being reshelved, each book will be individually inspected and vacuumed. Any book damaged by the pests will be set aside for later restoration work.

The abbey, which hopes to reopen the library at the beginning of next year, believes the effects of climate change played a role in spurring the beetle infestation as average temperatures rise rapidly in Hungary.

Hajdu, the chief restorer, said higher temperatures have allowed the beetles to undergo several more development cycles annually than they could in cooler weather.

“Higher temperatures are favorable for the life of insects,” she said. “So far we've mostly dealt with mold damage in both depositories and in open collections. But now I think more and more insect infestations will appear due to global warming.”

The library’s director said life in a Benedictine abbey is governed by a set of rules in use for nearly 15 centuries, a code that obliges them to do everything possible to save its vast collection.

“It says in the Rule of Saint Benedict that all the property of the monastery should be considered as of the same value as the sacred vessel of the altar,” Ásványi said. “I feel the responsibility of what this preservation and conservation really means.”