Marshall - 5:31 pm on Apr 22, 2008 (gmt 0)

Taking the image down is the right first step. Generally though, you do not buy the copyright when it is on a site for sale. You get a limited, non-exclusive, use agreement. Depending where you bought it, your proof is either: a - you could not download it without paying for it, or b - a receipt. If you do not remember where you got it, (a) is problematic. As for (b) if you did not save an email receipt of purchase, this is a rude lesson in remembering to do so.

As for legal action, here in the US, generally once you are sent a cease and desist notice and you comply, that is the end of it. Otherwise, if it is copyright protected, here you can be sued for actual loss, punitive damages and legal fees. I cannot speak to the laws in the UK.

One thing you can do is ask them for proof of copyright ownership. They could be blowing smoke.

Marshall