Why was Bethnal Green Tube disaster memorial delayed?

The worst civilian disaster of World War II is being marked on the 70th anniversary of the Bethnal Green Tube disaster.

A total of 173 people, including 62 children, died in a crush on 3 March 1943, when people rushed to enter the station after hearing air-raid sirens.

The alarm turned out to be a test.

Dr Toby Butler from the University of East London, who is leading a project to record the memories of survivors and rescuers and the relatives of those who died, said it was ''a puzzle'' why a memorial had not been realised earlier.

''This was wartime and there were concerns about morale,'' he said.

The trauma of the event was also a factor, he added.