A former bomber pilot has revealed one of the secrets of the Cold War – exploding chocolate teacakes.
The treats were carried onboard V bombers during the 1960s for crews to eat.
But the Tunnock’s teacakes were banned after they exploded at high altitude.
Former squadron leader Tony Cunnane, 78, who joined the RAF in 1953, said: “Crews would take lots of rations on long flights to snack on.
“One day we were given teacakes by chance and the crew loved them so we asked if we could have more.”
Crews noticed the mallow in the teacakes would expand as the air pressure changed at altitude giving an indication of height.
Experiments on effects of altitude pressure continued until several were left unwrapped on the instrument panel of a V bomber – and exploded on a test flight.
Tony, of Wakefield, added: “We noticed that the teacakes would swell and expand when we reached high altitudes and the chocolate would crack.
“It became a bit of a signal to the crew when the altitude was increasing and during one flight, someone noticed that as the cabin altitude increased above about 15,000 feet, the marshmallow in a teacake would expand.
“Word quickly spread and this discovery kept different crews fascinated for weeks.”
The teacakes were carried on V bombers stationed at Gaydon airbase in Warwick for six weeks during the summer of 1965 before one exploded during a training mission – ending their days as an inflight snack.
A spokesman for Tunnock’s, Britain’s biggest teacake maker, said: “It never ceases to amaze us what people get up to with our products.”