Brady and his New England Patriots will take on the St Louis Rams at Wembley on Sunday, and for Brady it is a second opportunity to help sell the game here after playing in the 35-7 rout of Tampa Bay in 2009.
The 35-year-old Brady is as close to a David Beckham-like figure as the NFL gets, given his film star looks, his supermodel girlfriend, and his long record of success in 11 years as the Patriots' starting quarterback.
If anyone can sell it to the British, Brady is the man, as long as he can avoid getting tangled up in the different meanings of the word 'football'.
"I hope the fans in England really enjoy the game," he said. "We certainly do in America. Hopefully the fans in England will root for New England too - hopefully that makes the most logical sense.
"But I know how much they love soccer and I don't think anything is going to get in the way of their rooting interest in a football team...or a soccer team...or whatever you want to call it.
"I get confused."
The NFL has hosted a regular-season game at Wembley each year since 2007, and next year there will be two.
The games have gone a long way to help grow the popularity of the sport, leading to increasing television audiences, merchandising and participation.
But there is still a long way to go, as the Rams quarterback Sam Bradford found when he met local children near the team's base at Arsenal's training ground.
"There's very little awareness as to what American football is and it was surprising just how little they knew about our game," the 24-year-old said.
"I think it's one of the great opportunities for the NFL to come over here. These kids aren't exposed much to football so if we want to grow our game we're going to have to do things like this.
"Some of the kids, it was the first time they'd ever seen an American football."
While the Rams have already arrived in London, choosing to have a full week of preparations in which to get acclimatised, the Patriots remain home in Massachusetts, due to arrive on Friday.
For them it is strictly a business trip.
"It was a great experience last time," Brady said. "The fans were loud, they were screaming the whole game and it seemed like we had fantastic support.
"We had the opportunity to practice at a famous cricket stadium (The Oval) and all the experiences were memorable, but for us the best part was to go there and win.
"As much fun as it can be, you still have to do your job. There are chances to go to London sightseeing but that's not for this trip."
Ever since the NFL's first Wembley game, there has been discussion about whether it can one day lead to a team being based here permanently.
But even as the league prepares to expand to two Wembley games next season, nobody is ready to answer that question yet.
"We're excited about the opportunity to play in London," Patriots coach Bill Belichick said. "But as far as the rest goes, that question is for somebody that knows a lot more about the world and league affairs than I do."