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Many are called, but few are chosen: Secrets of MI5 watchers revealed

Despite advances in electronic surveillance, security service MI5 still relies on human ‘watchers’. Government documents reveal what it takes to follow suspects without being detected

Bill Goodwin
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Published: 14 Jan 2025 9:30

Though many apply, only a few have the skills and patience to make it as a “watcher”, an MI5 training manual published for the first time by the National Archives reveals.

Despite the rise in electronic surveillance, watchers still play a crucial role in following and observing suspects to gather what might prove to be important snippets of intelligence.

A successful watcher is a “rarity”, says the anonymous author of MI5’s guide to “observation”.

“Hundreds of men have been interviewed as prospective trainees, but very few have been accepted, for the reason that when tried out, they are found to lack one essential qualification: viz patience,” the presumably male trainer writes. 

The ideal watcher should not be too short or too tall, and they should look as unlike a policeman as possible.

They should be nondescript, and have good eyesight and hearing to allow them to overhear conversations when the opportunity arises.

Dress style

Dress style is also important. A watcher must wear old clothes, such as a cap or a muffler “in the slum quarters”, and be better-dressed in the West End.

“A false moustache or beard is easily detected, especially under the high lights of a restaurant, pub or in a tube train,” the trainer warns.

An accurate report of a suspect’s movements is essential for testing the accuracy of a suspect’s statements.

And getting spotted by the suspect is a fatal mistake that could result in serious harm to an investigation.

Identifying a suspect at a known address can be a difficult job, requiring time and a process of elimination if no recent photograph or description is available.

Watchers are told to keep a distance of 25 to 30 yards behind the suspect and to walk on the opposite side of the pavement. Ideally a second watcher should also follow on the same side of the street as the suspect.

What to do if a suspect jumps on a train

The manual advises: “Be prepared for the suspect to board a moving vehicle such as a bus, tram or train, or hail a cruising taxi, or any such device to shake off a ‘tail’.

Watchers are urged to have plenty of spare change with them to buy a ticket in case the suspect jumps onto the Underground. On escalators, MI5’s advice is to gradually move closer towards the subject as it reaches its destination. 

“When he is suspicious, a suspect will often board a train just before the doors close, making himself the last one on the train, or he may alight at the last moment: so do not give him any rope on such occasions,” watchers are told.

If a suspect enters a restaurant or a café, it is essential to memorise a description of the people he meets. Be ready for a quick exit, with plenty of loose change to pay the bill without being delayed by the cash desk.

Finding the home address, street name and house number of a suspect is difficult during conditions of wartime blackout. 

Watchers are advised to observe whether the person being followed uses a key, knocks, rings the bell, or enters by a communal hallway, as that can provide clues as to whether he is a visitor or a resident. It may be necessary to return early the next day to verify observations.

Car chases: Offer cabbies a good tip

For watchers that find themselves following a suspect in a cab, a good tip for the cabby is a prerequisite. The MI5 instructor suggests watchers “enthuse a little extra activity into the driver in order that he may avoid the suspect’s detecting the following cab in mirrors or from the rear window”. 

If a suspect buys a train ticket, watchers are told to move in to overhear the destination, so they can buy their own ticket and continue the chase.

Post offices are particularly useful sources of intelligence, the guide notes. If the suspect goes to a writing desk, it is often possible to get a brief glance at the name or address of a letter or telegram. A watcher can also learn a lot by standing close to the suspect at the counter.

To avoid getting spotted themselves, watchers are encouraged to leave home, walk around the block, return, and start off again in another direction heading away from the most direct route to his assignment.

“He will know his own neighbourhood intimately and use such knowledge to alternate his means of conveyance by bus, tram or train, but always gradually making towards his objective and ascertaining at the same time if he has a ‘tail’,” the manual reads.

Illustration on page five of the manual

MI5 still relies on highly trained “watchers”, these days rebranded as mobile surveillance officers, to follow suspects and gather intelligence.

These days, watchers are just as likely to be women as men, and represent a diversity of ethnicities.

But the wartime manual may be right on one thing: the ideal watcher is born, not made. As the manual notes, “unless he has a natural flair for the work, he will never rise above a mediocre standard”.

Other documents released by the National Archives

  • MI5’s investigation files into Hollywood actor Dirk Bogarde, following information that Russian Intelligence had approached a young actor while visiting Moscow. MI5 found no grounds for suspicion.
  • Files dealing with claims that Russian intelligence agent Constantin Volkov had made to the British embassy in 1945 that Russian spies were working in the UK government. Russian intelligence was tipped off and Volkov disappeared. MI6 double agent Kim Philby was suspected of tipping off the Russians.
  • A telegram from Washington stating that MI6 counter-intelligence officer, John Cairncross, later identified as the “fifth man” in the Cambridge spy ring, had admitted spying for Russia. 
  • An account of an interview between an MI5 interrogator and MI5 officer Antony Blunt, in which Blunt confesses to spying for the Soviet Union. Blunt, the “fourth man” in the Cambridge spy ring, passed on secrets including German communications decrypted by Bletchley Park to Russia. He was responsible for recruiting Cairncross.
  • Kim Philby’s typewritten confession – largely considered unreliable – which he handed over to an MI5 officer in Beirut, admitting that he spied for Russia between 1934 and 1946. Philby admitted tipping off Donald Maclean, another member of the Cambridge spy ring, that his cover was about to be blown, resulting in his defection to Russia with Guy Burgess.

MI5 and the National Archives will feature an exhibition on the work of MI5 at the National Archives in Kew this spring. The exhibition, the first in MI5’s 115-year history, features original case files, photographs and papers, and espionage equipment, alongside videos of former MI5 directors general.

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