The left back, signed from Walton and Hersham for £40,000 after dropping out of professional football with Chelsea as a teenager, has initially joined on loan in order to play at Bradford on Tuesday evening, and he says: "It is a good move for me. I went to Peterborough and have played over 40 games this season so I must have been doing something right.
"There were a few clubs interested and Steve Bruce said he would give me a chance at the next level, so I am over the moon."
Although reports of a £1m fee might be somewhat exaggerated, West Ham will take a substantial amount of it by way of compensation for rescuing Tom's career.
He was working in a bank when West Ham signed him two years ago, and thanks the club for the grounding given to him in his year at Upton Park.
"The coaching there was good," says Tom, "and Glenn said that I needed to play games, so it proved to be the right move.
"In a way I'm surprised by the fee, but that is what today's prices are for a player of my age that is not doing bad.
"It is small compared to what everyone is going for but it is just pleasing that I have been recognised and I am moving on again.
"It is strange because this time last year I was going on loan to Peterborough because I needed games to get experience - hopefully I can get some games at Birmingham now, and West Ham will get half the fee."
Tom reckons that another former West Ham player, Jimmy Bullard, will also step back up after he too was taken out of non-league with Gravesend and Northfleet before joining Posh on a free.
"He is doing well with some dogged performances in central midfield, and he is scoring goals. I wouldn't be surprised if Jimmy secures a move somewhere as well," says Tom.
Another former West Ham player, Aussie defender Steve Laurie, is also at Peterborough United, having joined on a free this winter.
Ironically, former left back David Burrows, who joined the Blues from Coventry City two years ago after leaving West Ham, has just had his contract paid up at St. Andrews, and Tom effectively replaces him.