A World War II airman's logbook could solve the 55-year mystery of the disappearance of American bandleader Glenn Miller.

The swing-beat impresario's plane vanished over the English Channel on 15 December 1944 and Miller was never seen again.

But the log-book of wartime RAF flight engineer Derek Thurman, from Derby, could provide an answer to how the hugely popular musician met his death.

The book was sold on Friday for $880 including buyer's premium on auction house Sotheby's internet sales site.

It tells of how a British air-raid on Germany, the night Miller disappeared, was sent back to base.

The 138 Lancaster bombers dumped their explosives over the sea - as was normal practice to ensure a safe landing.

Mr Thurman said three crew members on his plane spotted a light aircraft below them, which they believed was brought down by the hail of jettisoned bombs.

"The three people who saw it were absolutely convinced that they saw a small aircraft going in the opposite direction when we released the bombs," he told the BBC Radio 4 Today programme.

"The raid was aborted when we were south of Brussels because our fighter escort couldn't get airborne and we had to jettison our bomb load before we could land.

"We went to an area that was specifically set aside for that purpose, that was clear of shipping and no other aircraft should have been in that area at all."

Each of the 138 Lancasters dropped a 4,000lb bomb and a number of incendiaries, he recalled.

"Nobody anticipated there being an aircraft there at all. There was a shout that there was someone there. The navigator shot out of his seat to look and saw it whip by, then the rear gunner said 'It's gone in, flipped over and gone in'.

"He must have been off track to be in that place at that time.

"Whether it was brought down by the blast from a bomb or was hit is anyone's guess."

When a similar document from the same flight was sold by Sotheby's last April, bidding eventually reached £22,000.