A 101-year-old woman was dragged along a platform after her coat got stuck in a tube train’s doors.

An investigation into the “trap and drag incident” in Archway station last year has called for a review of sensors in the doors that “cannot detect relatively thin objects”.

The elderly passenger whose coat got caught in the doors had to be stretchered out of the tube station before being taken to hospital by ambulance.

“She sustained serious injuries and has continued to suffer from the effects of the accident,” according to a report from the Rail Accident Investigation Branch (RAIB).

“The passenger and their companion both realised that the coat was trapped and tried to pull it free but were unable to do so.

“The companion tried to offer some protection by holding the passenger as they both fell.

“The combined weight of the falling passenger and companion pulled the coat free of the doors.”

When all the doors close on a tube train a “pilot light” goes on on dashboard alerting the driver that they can set off.

The train driver was not aware that a passenger’s coat had been trapped in the doors on the Northern line at Archway

But the RAIB report – which also investiga­ted a very similar incident in Chalk Farm station last year – said this door system on most trains is designed to detect an object only “with a minimum thickness of 11mm”.

It said that previous investigations had found most drivers believed that a pilot light that switches on when the doors closed meant nothing could be trapped there.

The report added that the “repetitive and monotonous nature of automatic train operation” can lead to train drivers not paying attention all the time.

It called on the London Underground to consider technology “that will detect when thin objects, such as fingers, straps or clothing, become trapped in train doors”.

It also suggested a review into “modifying door seals to make it easier for small, trapped objects, such as clothing and straps to be pulled free from closed doors” and “improving the images presented to train operators”.

There is a one in four million chance of being trapped and dragged down the platform by a tube train, the London Underground said.

Nick Dent, London Underground’s director of customer operations, added: “The safety of our customers and staff is at the heart of everything we do and we were extremely concerned that two customers were injured at Archway and Chalk Farm last year.

“London Underground is consistently recognised as one of the safest metro systems in the world, carrying millions of customers every year.

“However we are not complacent and we welcome the recommendations from the RAIB’s report and we are in the process of implementing them.”