Why did he do it?
The Story of a Royal Air Force Pilot Who Scared Everyone by Flying Close to National Landmarks in London
Knowing that he was likely to be stripped of his flying status as a result of this display, he proceeded to “beat up” several airfields (Wattisham, Lakenheath and Marham) in inverted flight at an altitude of about 200 feet en route to his base at RAF West Raynham, where, within the hour, he was formally arrested by Flying Officer Roger Gilpin.
The so called Hawker Hunter Tower Bridge incident occurred on Apr. 5, 1968 when Royal Air Force (RAF) Hunter pilot Alan Pollock performed unauthorised low flying over several London landmarks and then flew through the span of Tower Bridge on the Thames. His actions were to mark the 50th anniversary of the founding of the RAF and as a demonstration against the Ministry of Defence) for not celebrating it.
In the 1960s, the British defence industry saw a shifting emphasis from manned aircraft towards guided missiles, originating from the 1957 Defence White Paper by British Defence Minister Duncan Sandys. The British aircraft industry had slipped into general decline and morale in the aerial services of the British armed forces was low.