FIRE and police crews were initially scratching their heads over a mysterious 'bang' heard around Oxford.

The explosion, in January 1967, was eventually traced to Magdalen Bridge, even though the sound had travelled as far as Headington and Cowley.

Dozens of police rushed to the bridge alongside firefighters and engineers, but the only sign of any damage was a small pile of stone that had crumbled from the wall, and a shattered window at Magdalen College.

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A witness said smoke was 'pouring' from the bridge after the explosion, so much so that cars were having to put their headlights on to see their way.

Experts concluded that there had been no structural damage to the bridge, and the most likely explanation was that someone had lit a home-made firework inside a metal canister.

At the time FP Tarling, deputy chief fire officer, said: "I suggest it was a practical joke, I would suggest that someone wants his backside kicked."