Mr Lait, who teaches dance in Cambridge, believes he and his dance partner Crystal Main were the only passengers in the carriage who survived the blast without serious injury – even though they were sitting nearest to where the bomb detonated.

When he came to, there was a body lying on top of him and he was surrounded by the dead and injured. But incredibly, the only wounds the dance coach sustained were facial lacerations and a perforated eardrum.

"I feel extremely, extremely lucky," he said.

The explosion happened just after Mr Lait and Ms Main, 23, got on the train at Liverpool Street on their way to the South Bank for a rehearsal.

He recalled that the carriage had about 20-25 people in it, from all walks of life, and aged from their teens to over 60.

"I remember an Asian guy, there was a white guy with tracksuit trousers and a baseball cap, and there were two old ladies sitting opposite me," he said.

"We’d been on there for a minute at most and then something happened. It was like a huge electricity surge which knocked us out and burst our eardrums. I can still hear that sound now," he said.

The impact of the blast made him pass out. As he came to, he wondered whether he was alive or dead.

"We were right in the carriage where the bomb was. I was knocked out. I did not know what was going on.

"I wondered if I was dead or not. I said to myself, you can’t be dead because your brain is having conscious thoughts, so concentrate hard. I was telling myself ‘wake up Bruce, wake up’."

Royal visit: At Royal London Hospital

Disorientated, he only gradually realised where he was and what had happened.

"When I woke up and looked around I saw darkness, smoke and wreckage. It took a while to realise where I was and what was going on, then my first concern was for Crystal.

"She was okay but she was in shock because she was trying to deal with the person on top of her who had massive head injuries. We have just found out that this person died," said Mr Lait, who lives in Suffolk.

He too was afraid to move because there was a seriously injured woman lying on top of him.

"I realised someone was lying on top of me. I tried not to move her because I didn’t know if she was still alive, or I could have made it worse. This person also died, while on top of me."

At the same time, he slowly tried to work out whether he or Crystal had been injured.

"I thought if I can wiggle my toes I’m okay, and I could, and I asked Crystal to do the same."

Describing the scene as they waited for help, he said: "It was just the most awful scene of death and there were body parts everywhere. There was something next to me. I was trying not to look. I couldn’t figure out what it was."

When paramedics arrived, they confirmed that the woman on top of him was dead and carefully moved her body. Mr Lait said the middle-aged woman had blonde curly hair, was dressed in black, and could have been a businesswoman.

He and Crystal were helped out of the carriage. As they made their way out, a policeman pointed out where the bomb had been.

"The policeman said ‘mind that hole, that’s where the bomb was’. The metal was pushed upwards as if the bomb was underneath the train. They seem to think the bomb was left in a bag, but I don’t remember anybody being where the bomb was, or any bag," he said.

They were led through the tunnel to the platform at Aldgate, which was just a few hundred yards away, and taken out of the station to wait for an ambulance.

Mr Lait was taken to the Royal London Hospital, Whitechapel, where he was visited by the Queen on Friday.

He said: "They asked would I mind if my name were put forward and I said I’d love to meet the Queen, even if the circumstances weren’t ideal."

Sitting with his parents, Pat and Tom, Mr Lait told the Queen as she stood at his bedside: "I’m very thankful to still be here."

He said of Her Majesty: "She just seemed very nice and concerned, she seemed very genuine."

Now back at home, he has been trying to recover from the ordeal, with the help of friends and family.

Mr Lait, who teaches the Latin formation team XS, based in Cambridge, and the Cambridge Dancers’ Club, said he has been moved by people’s care and consideration.

On the floor: Bruce & dance partner Crystal, who was also on the train

"I’ve had people who know me phone me from all over the world and ask if I am alright. Those pictures of me and the Queen have gone all over the world."

And he said the terrible experience has given him a new outlook on life.

"It has made me realise how important life is, and that we only get one life, and we’ve got to be happy with what we’ve got in our lives."

Reflecting on the ordeal, he said: "Out of that whole carriage, I think Crystal and I were the only ones who were not seriously injured, and I think we were nearest the bomb.

"It makes me thank Him up there. I’m not overly religious but I’m not a disbeliever. I pray now and again. Something like this has just made me think, ‘thank you Lord’."