Advice for 'herding the cats in my county'

I'd suggest adding some sort of social media element as well. A Facebook group has served our local polo community well, since it is an easy way to keep in touch with people once you've recruited them.

Starting out, I'd do one night a week. Better to have one solid night each week for the first while, rather than a few nights with the potential of not as many people showing up.

If you have not locked down a place to play yet, location, visibility and accessibility by bike are all pretty key.

Aside from flyering shops, etc, you can flyer bikes (if you see bikes that seem to fit the polo scene a bit more).

Consistent communication & times are pretty key when you're first starting out. It only takes one instance of having nobody show up to turn some people off, so you need to be prepared to be the first one there and the last one to leave for a few months or more, at least until other people start to take the reigns.

Good luck.

The facebook thing, flyers and having mallets at the ready are good suggestions.

Also, I've found that posting an ad in the bicycles, groups and/or activities sections of Craigslist for weekly bike polo have brought out more than a few curious people in Phoenix, some of which have actually stayed on & become regular players. I've done it in my little town in California where I live now, with similar results. If you don't have Craigslist in your area of the UK, maybe something similar would do the trick.

As far as a place to play (courts), try to find a place with the most public exposure as possible (not THAT kind of public exposure, you perv), similar to what Liam said. The optimal location will be in a high foot traffic (or high bike traffic) area that when passers-by see you playing, they will be inclined to stop and watch.

As far as flyers, also similar to Liam's advice, put them in people's spokes!!!!! We had some in AZ a while back that said something like "Hey, I see you like bikes, you should check out bike polo, here's where/when we play etc". Make it a non-obtrusive message and someone will be bound to respond positively.

Oh, and bugging the shit out of all your friends to come and check it out is another option. After awhile, they'll get so sick of you badgering them that they'll come out some night & hang out. And chances are that they'll either dig what you're doing & try playing, or they'll tell their friends about it (I.E. on Facebook, "I just watched bike polo for the first time") and some people will be curious.

If/when people show up out of the blue, be as kind and encouraging as possible. Go out of your way to make them feel welcome, and sometimes they'll come back a second time just because you were so nice to them.

EDIT: Also try hitting up your local newspaper/TV news channel. Many times, since they've never heard of bike polo, it will sound like a novelty to them, and they'll come out and do an article/segment about it.

Good luck!