Now the defensive line coach for the San Francisco 49ers, he is intent on helping to extend his team's winning run to five games when they meet the winless Jacksonville Jaguars.
Tomsula, who was a coach at London Monarchs before joining the Claymores, was part of the 49ers' coaching staff on their last trip to Wembley - when they lost to Denver Broncos in 2010. Mike Singletary was sacked as head coach of the 49ers at the end of that season, with Tomsula taking over for one game before Jim Harbaugh was appointed as permanent head coach ahead of the 2011 campaign. He guided them to last season's Super Bowl, where they lost to Baltimore Ravens.
As he prepares his team to face the Jaguars, Harbaugh stressed there was never any doubt that he would retain the services of Tomsula when he came into his new job. "When I first got hired two-and-a-half years ago, I interviewed all the coaches and, no, it wasn't a tough decision to hire Jim Tomsula," he said.
"He's had a special gift of presence, personality, of teaching ability and that came shining through. I remember that first meeting. That's one position I've just never had to worry about since I've been here as the head coach, the defensive line position. He's always got them ready to play."
Tomsula has been coaching at high school, college and professional level since 1989 and, between NFL Europe seasons, also coached Division II Catawba College in North Carolina, where he had played as a defensive lineman until a knee injury ended his playing days.
Now 46, he had previously spent two seasons out of the game between 1995 and 1996 when he held down various jobs including medical rep, night janitor, delivering newspapers and chopping wood. When Tomsula returned to coaching in 1997, it was a voluntary position with Catawba College while he worked as a carpet salesman and even lived out of his car to make ends meet.
"None of us look at it as a sacrifice, though," said Harbaugh. "Coaching is a great honour and a great privilege, to be able to teach and do all the things that make you keener, finer, more alert. If that means sleeping in your car to be a better coach, then by God, that's what you do. He's got a great love of the game that shows every day."
London Olympian Lawrence Okoye, who reached the final of the discus last year, is the latest athlete to come under Tomsula's wing, having signed as a defensive tackle for the 49ers in the summer. He will miss Sunday's match due to a knee injury but has been acting as unofficial tour guide for his team-mates this week, having been brought up in Croydon, where Tomsula also lived when he was coaching at London Monarchs.
Okoye remains a work in progress but Harbaugh believes he brings value to the team. "Many things struck me about Lawrence, and our coaches, that were exciting [such as] the fact that he was a rugby player, a tough sport that [American] football evolved from," he said.
"The fact that he went and started throwing the discus and in two years was at the Olympic level, that spoke volumes. You wanted to see what would it be like if he switched to football and how quickly he could grasp that. There have been some positive signs. He's on the right track and it's got possibilities still."