A pilot over the alcohol limit about to fly over 300 passengers across the Atlantic was taken of the plane by armed police.

Allegedly security staff smelt alcohol on Daniel Dufour’s breath when he went through routine checks at Heathrow’s Terminal 5.

Police then removed the Canadian captain from the plane in front of shocked passengers and crew. Dufour had been drinking the night before with colleagues, failed a breath test and was arrested.

A police source said “He was amazed to be still over the limit in the middle of the day.”

Dufour was then taken to Heathrow police station to give a blood sample and was bailed for further inquiries.

He was only minutes from take off for the nine hour flight to Calgary on Air Canada flight AC851.

The source said “He was close to tears. At this stage he appears to have thrown away his distinguished career.”

A reserve captain was later called in to fly to Calgary.

The legal alcohol limit for pilots is 20mg per 100ml of blood which is a quarter of the maximum for drivers.

Scotland Yard said “A man was arrested on suspicion of performing an aviation function whilst exceeding the alcohol limit. He was bailed to June 12.”