Thanks to all for the feedback. Re referalls, I used to get a few calls from people who said I'd come recommend when I lived in a ruralish community in Wales, but not in Colchester, even when I know darn well that someone has passed on my details.
Knappers probably has a point about seeming too cheap at times, so it may be people don't think of me as a 'proper' plumber, and I suppose it leads to trying to compete with semi-retired and the like who work for beer money. Or that because I tend to do the hidden work such as shower pumps and not the flash stuff that gets noticed like bathrooms, it isn't the kind of work that gets people interested?
I don't want to undermine the industry/be the source of unfair competition, so it is interesting to hear Knappers say he's charging 300 plus. I will keep an eye on it, and think about my prices again in April with the new tax year.