Sighting of Glenn Miller's doomed plane by amateur spotter shatters theory that aircraft was downed by falling WWII bomb'

Mystery: The cause of swing musician Glenn Miller's death in 1944 has sparked many conspiracy theories

For almost 70 years, Glenn Miller's death in a wartime plane crash over the Channel has been a source of fascination and speculation.

Neither the great American bandleader's body nor the wreckage were ever found, leading to countless claims of a cover-up.

But now a previously unreported sighting of the doomed plane has emerged in a teenage planespotter's notebook – and seems to shatter the main theory over Miller's death.

The popular explanation suggested that after taking off from England on December 15, 1944, for Paris, where he was due to give a series of morale-boosting concerts to troops, Miller's Norseman light aircraft was hit by a bomb jettisoned by an RAF Lancaster returning to England after an aborted raid on Germany.

But now it has emerged that Richard Anderton, then 17, jotted in his notebook how he saw Miller's plane that day east of Reading – and west of London – flying in an east-south-east direction towards the Sussex coast.

The timings suggest the Norseman was miles away from the bomb jettison zone over the Channel.

The significance of the sighting was established after the notebook was taken to a BBC Antiques Roadshow event for valuation by relatives of Mr Anderton, who died in 1982.

The Notebook: The Glenn Miller archive in Colorado is satisfied that the highlighted line '1 Norseman going ESE' refers to Miller's plane

Eyewitness: Richard Anderton who noted his sighting of Miller's plane in his logbook

It supports the original, official version of events that Miller's plane crashed in the sea due to pilot or mechanical error.

Dennis Spragg, historian at the Glenn Miller Archive in Colorado, U.S., which has authenticated Mr Anderton's sighting, said: 'One theory for the cause of the crash was that the pilot strayed east into a restricted zone for bombers and the plane was struck by friendly fire.

'But by December 1944, when the Allies were in control of northern France, it would have been extremely problematic to have a bomb jettison zone off the south coast because of the location of transport routes for aircraft and pipelines under the Channel. It is likely the restricted area was further east towards the North Sea.

'This document is very important because it shows the pilot was flying on the right route and was on schedule and didn't fly to the east as speculated.'

Other more outlandish theories have suggested that Miller, best known for his hit In The Mood, was a spy and made it to France, or was captured by the Germans.

Mr Anderton's notebook, valued at £1,000, is featured on the Antiques Roadshow tomorrow. He was working at a factory at Woodley Airfield in Berkshire when he saw the plane and made a note of it.

But he did not realise it might be Miller's until 1969 when he read a newspaper article about him. He didn't mention it to anyone, and it was only after he died that his family found the notebook.

A plane similar to the UC-64 Norseman light aircraft Miller was flying in