Hello Alex,
Sorry to see you didn't get a massive response to your original post earlier in the year. Did you follow it up anywhere else with any degree of success?
I'm fairly new to parkrun - the local one I go to in London has built itself up to a turn-out of about 90-100 people at the moment and it's a nice atmosphere, and I'm going to try and go along whenever I can. I also like the idea of there being others around the country that I can participate in if I'm visiting the local area and can fit one in. A few members of local clubs attend each week (depending no doubt on their other weekend race commitments), but the majority of runners who take part are Unallocated.
I make 2 or 3 trips to Southend each year and when I was there last month ran along the sea-front - there was a huge number of people out running (and a lot more people smiling and saying hello than I'm used to in London!), so like Wilkie says, there is bound to be quite a bit of interest. I guess it's just getting the message out, maybe through local clubs, leisure centres, that sort of thing - it might be that if you contact the parkrun organisers direct, they can give you some tips too.
So although I'm afraid I can't offer local support, I'm sure there would be a sufficient number of people who would jump at the chance to participate, and I would certainly try and come along on the few occasions when I'm in that neck of the woods.
All the best,
Gavin