I'm just kidding about that, I know a few rugby guys who say that because american footballers wear protective clothing under their jerseys. I'm sure Jeremy Clarkson has mentioned something similar before.
Make no mistake about it, soccer is number 1 here by a large margin and then it's rugby but I honestly couldn't tell you why the NFL is so popular here when it comes. It's the same with the superbowl, I know people who will only watch american football that one night at 1am religiously every year. I think it's just an excuse to stay up late and drink on a SUnday.