I may be wrong here, but I don't think a URL qualifies as a trademark or legal business name. If you were the first person to grab (for example) www.harrods.co.uk before Harrods grabbed it, then you'd be entitled to use that URL. In fact, a number of people bought up URLs of potential websites in the early www days - just so that they could possibly be bought out, for a price, by the firms or institutions who wanted them.

So, unless web registration has changed in principle, www.FolkDirectory.co.uk can be quite legally used if you own that URL.