Wheel Maintenance in London UK

Thanks everyone who has given so much good advice on recent glaze chemistry queries. My old Britannia Wheel has still got a case of the shakes. Some of you might remember I posted a request for help some weeks ago and received some good suggestions all of which have been tried including buying a new drive wheel. However the problem still exists. The new drive wheel helped to a certain extent but there's still too much judder to cope well with even small ware. Can anyone recommend a WHEEL ENGINEER or maker within easy reach of north London (UK)? We're desperate as we've got our first selling market in November and much to do. Thanks again Pete