"They didn't do kids [sizes] back then so mine was a small mens. I was about nine and it was huge on me but it's all I'd wear. I used to wait for mum to wash and dry it, standing beside the washing machine, so I could put it straight back on. I've got pictures. I wore it to school, I wore it everywhere.
"As a kid, I was always one of the smallest and I used to see Langer, who is absolutely tiny compared to other blokes, and he would go on and kill it. I think he was the first player who inspired me to go on and do something."
Tomkins did. In his first game for Wigan, at just 18, he scored a hat-trick inside the first 12 minutes; he finished with five tries on debut.
"We were in the Challenge Cup so we were playing a side in the league below us and we won 108-10," he recalled. "The next morning, I was front and back page of the paper. I don't know if you know much about Wigan but rugby league is a religion there."
He's become the player they worship. Since his debut in 2008, Tomkins has helped the Wigan Warriors to two Super League titles and two Challenge Cup crowns as well as being voted last year as the Super League's Man of Steel.
He's about the only English rugby league player who has a column in the major papers. As for the Burgess brothers' family fame, the Tomkins boys are a bigger deal. Sam's older brother Joel made his debut for the England rugby team last weekend in their win over the Wallabies. A third brother, Logan, plays at Wigan. He credits their parents for their success.
His father, a police officer, and his mum put their lives on hold to look after their boys to drive them where they are today.
That's how Sam came to sign his deal at the Warriors. His mum toured the New Zealand headquarters and returned home and told her son to pack his bags. Tomkins admits other NRL clubs came calling but won't say who.
As for his own expectations, he wants to take over Billy's crown.
"To be mentioned in the same breath as someone like Billy Slater is a little bit humbling. Every player wants to be the best in the world at their own position, it is a goal but it is a long way off.
"But timing-wise, for me, this is perfect. I'm 24 and I've really loved the last six years at Wigan but I'm looking at this as an opportunity.
"There will be eyes on me and expectation because of the the transfer fee. But I don't let the fee bother me. I didn't pay it and I don't get any of it.
"It is nice to think the Warriors think that much to pay a substantial amount but I'm looking to come in and perform on the field.
"That's my aim. Whether I was coming over for 10 the main reason we all play is because we are competitive and I want to be successful. I won't need any more motivation than that. I want to win."