Meh. Watford is part of London. I know it technically isn't, but it basically is. It has tube stops.
Norwich's metro is closer to 375,000.
As Denzil mentions, 'metros' don't mean that much in a densely populated country like Britain with many polycentric regions and near continuous settlement.
Football is largely a matter of identity for cities, towns, boroughs, districts and so forth rather than large 'metros'. Otherwise there would only be about 10 clubs as there aren't that many major metros. Yet there have been about 50 clubs in the Premier League to date - and some of the large metros such as Sheffield or Leeds aren't represented this year or haven't been represented in several years.
Watford might be very close to London but that doesn't benefit the club all that much. It helps in some ways because there's more money in outer suburban London than in formerly industrial Yorkshire or the West Midlands. But it also hurts the club because they have to compete with the bigger London clubs for fans. Their market really is only Watford and the surrounding areas of Hertfordshire.
Huddersfield itself is just a few minutes' drive away from Halifax and Brighouse, two sizable towns. It's only about a 15 mile drive to both Bradford and Wakefield. And it's still an easy matchday drive from Manchester and Leeds. It's a pretty densely populated area. Yet it'd be wrong to say that all those areas are natural reservoirs for Huddersfield Town fans. Huddersfield Town as a historically fairly mediocre club has no appeal beyond its immediate surroundings.
And that's my point here. Huddersfield are about as classic a lower league club as one could find and that's what makes them utter underdogs in the PL. But the comparison to some similar-sized 'market' playing in a major league is misguided because the town size isn't what makes Huddersfield a special case. The PL isn't a league of franchises placed in major cities.
I may add that Kaiserslautern won two Bundesliga titles in the 90s and that town has just about 100,000 souls. Aside from the club and some major U.S. military installations there's not much there. What allowed them to compete at the top of the German game was a rich history and thus a large fanbase across an entire region.
) Aston Villa are also winless in their first three but in fairness their fixtures to start the season is tough
