A BOMB scare plunged tube services to Chiltern stations into chaos causing widespread commuter misery.

Passengers were relieved after planned strike action by underground staff was called off on Wednesday. But two days earlier rush-hour passengers travelling to Amersham, Chesham and Chalfont and Latimer stations were stranded for hours when trains ground to a halt after a security alert.

The scare was sparked after a driver discovered an abandoned bag containing a grey substance at Rickmansworth station, just after 3pm.

Bomb disposal experts called in by police identified the mystery substance as modelling clay but the alert caused havoc for more than four hours.

Some passengers had to take trains to High Wycombe and hail a cab to get home.

Amersham station was at the centre of a similar alert last Wednesday when a train driver spotted an unattended bag on a train.

Donal O'Riley, spokesman for London Underground, admitted the bomb scare had gone on longer than it should have.

"It was all completed by 7.30pm to 8.15pm when services returned to normal," he said.