What began as deep shock led to wide-ranging questions about a life which, until Thursday, he took for granted.
Yesterday he remained at home, unable, as yet, to resume his commute into central London from the north of the city.
"I know I'm going to have to do it but it's going to be difficult," he said. "What happened ... is not something you are going to forget. Over the last couple of days, I've asked myself why I go into work.
"I know I can't go back on a packed train so I will go to work before or after rush hour. It takes a massive lift of energy and guts to do the journey."
Mr Spelman was in the third carriage when the train exploded near King's Cross. He emerged without serious injury but deeply shocked.
He regretted making the decision to take a short Tube journey on Saturday which took him back to King's Cross.
"It was really awful and worse than the experience of being on that train on Thursday itself. I actually wanted to go up to someone and say 'Can you come on the Underground with me?'. The train made a funny screeching sound at one point and I thought 'Oh my God'. It was just awful to return to the station where it all happened."
He has been plagued by "moments of panic" and feelings of guilt. "After having been so calm at the time, it has now really kicked in how serious it was, and all the poor people who were left down there."
Mr Spelman, who is married and has two children, plans to minimise Tube travel in future, but wants to return to normality. "It's like falling off a bike. They tell you to get straight back on again. I'm going to get back on and ride like crazy.I'm going to make the shortest possible journey for the next couple of weeks. I don't want to do many stops or go to King's Cross or go into long tunnels."
Despite his anxiety, he was certain he would not let the experience overwhelm him. "If you don't go back, you end up destroying yourself. I have lived in London through all the bombings of earlier decades and I have never let anything stop me from going to work so I can't let that happen now."Reuse content