Okay,I am familiar with Berwick upon Tweed as I have lots of relatives just down the coast from you in Northumberland.. everywhere from Lesbury, to Cramlington to Newcastle on Tyne. Berwick upon Tweed is a beautiful place to sketch.
I was actually sketching a scene from Lesbury today from photos to send to one of my relatives..... Sorry I am not closer but I am in Vancouver, Canada, not so easy to meet with you in person.
I have not seen any sketch groups on Sketchcrawl for that city. I see you already have a Flickr site and aren't you with Urban Sketchers?
The best way to get a group together for SketchCrawl is to check back to this site periodically and wait until Enrico Casarosa to announce the next couple of World Wide Sketchcrawl dates (don't hold me to this but they will probably be Jan and Apr 2012 on the closest Saturday to the 15th of the month). Then when the Sketchcrawl #34 Posting goes up, then go in and create a thread with label Berwick-upon-Tweed, UK. Announce in it who you are and that you wish to see who else from that town wishes to participate in the Sketchcrawl. If you don't get any hits after a week or so, I suggest you check around the local art stores and with other artists and invite them to come out. They do not have to stat out of be members, they don't even have to be artists, just people that are interested in going out and sketching for a few hours.
You do not have to wait until the next World Wide Sketchcrawl. Suggest you try looking out for one or two people that want to go out and do a mini-scetchcrawl. Results of these can be posted under Random Sketchcrawls.
Also check back through the old Sketchcrawl threads and see if there are sketchers from nearby cities and towns that are willing to meet.
Message me if you have any questions or you need help.