Sitting in the corner of a north London gastropub at a dark wooden table beneath a chalk board advertising the day’s specials, three elderly men inconspicuously sip their drinks.

Unknown to punters at the Castle in Islington, the pensioners were discussing the spoils of the Hatton Garden jewellery heist, the biggest burglary in English legal history, for which they had – at that point in time – evaded capture.

But Flying Squad detectives knew exactly who they were and what they had done when they covertly filmed Brian Reader, 76, Terry Perkins, 67, and Kenny Collins, 75, in the pub just off Pentonville Road, on 1 May.

The venue is perhaps an unlikely setting for these white-haired, bespectacled customers to reflect on the £14m raid they had spent months so meticulously plotting, with its craft ales, Cornish crab fries and duck cottage pie.

Surrounded by young professionals from the likes of nearby Ticketmaster and the Craft Council, Reader, Perkins and Collins, as well as co-conspirator Daniel Jones, 60, met at the drinking hole on Fridays, devising how they would break into the Hatton Garden Deposit Company over the Easter weekend, drill a hole in its concrete vault and make off with diamonds, gold and cash. Later, they would return to discuss how they would shift the loot, melt it down and cut it up.

Jennifer Cullen, 27, who works nearby, rushed to the pub on Friday lunchtime to sit in the exact same seats in which Reader, Collins and Perkins are pictured in the newspapers.

To her disappointment, staff had covered the table with paperwork and it was out of bounds. “They planned the whole thing here,” Cullen said. “The table was just over there. The guy didn’t want to move his stuff so we couldn’t sit there.”

The Castle is owned by Geronimo Inns, a subsidiary of Young’s Brewery. Young’s have placed staff at the pub on lockdown; they are not to discuss their now notorious former customers.

Cullen does not understand why the staff are being discouraged from discussing the raid as the pub’s association could be good for business. “Surely they would welcome it as it will bring in more people,” she said. “There are morbid fascinations with crime, like Jack the Ripper, people are interested.”

Cullen said the Castle is not the sort of pub in which she would expect career criminals to plan a historic jewellery heist. “They took their time to burgle the place, it was a bank holiday weekend and they returned again,” she said. “I know they’re criminals but I have to say it was a pretty impressive plan.”

Another customer in the Castle said the pub was “a lovely boozer”. “It’s at the top end, it isn’t a cheap pub, you might only come here for special occasions. I’ve been here on a load of Tinder dates.”

But not all the customers are aware of their surroundings. A group of Spanish tourists seemed indifferent to the fact that at a table a few feet away, four men plotted a burglary that captured Britain’s imagination.