As investigators piece through the wreckage of the Paddington rail crash and work out just how many people died, scores of families wait for news.

Just because someone who may have been on either train has not returned home, people may well be asking themselves, should they think their loved one died in the crash?

The identities of most of those who died may well be established, but some may not. Even now, 12 years after the King's Cross fire, one of the victims has not been identified.

And even if the deceased are identified through teeth or jewellery, how does one come to terms with the death of a loved one when there is no body to see, cremate or bury?

It is a concern shared by the Bishop of Reading, the Right Reverend Dominic Walker, who has set up a shrine so that the bereaved in his diocese can have some focus for their grief.

"Some of these people will have no body to bury, and no focus for their mourning, so it makes it all the more difficult," he said.

Thousands of survivors of the Turkish earthquake had to mourn without the bodies of the dead

The difficulties are a perfectly natural human response, says Dr Peter Hodgkinson of the Centre for Crisis Psychology, who has worked with relatives of several recent disasters.

When no body is recovered, he said, for the family "there is no rational ground for accepting that the death has occurred".

"People will imagine that maybe the person was involved, but has maybe lost their memory and is wandering around somewhere, or perhaps that they have gone away to think about it."

He had spoken to the grandparents of a baby who had died at sea, but whose body wasn't found. A year after the death, they still imagined the baby had been washed ashore and was being looked after by someone.

"It's an absolutely rational reaction, and nobody can gainsay it," he said.

It is not made any easier by the knowledge that people do simply disappear. After the Herald of Free Enterprise sank, relatives of three times as many people as were on board telephoned to see if their already-missing loved ones had gone down with the ship.

"People desperately want closure, and will go to any length to achieve it. They are desperate for knowledge."

Not about forgetting

Lorraine Sherr, a consultant clinical psychologist at the Royal Free Hospital in London, said it has been recognised for some time that grief needs a focus.

Mourning was not about forgetting, she said, it was about remembering people's lives and qualities.

"In order for that to happen, there has to be somewhere to start.

"The most difficult things to cope with after a tragedy are the feelings generated because you have survived while others have not.

"Also there has to be a realisation that life will never be the same again.

"Those emotions are easier to come to terms with if the process of grief has been properly embarked upon."