Wow... I couldn't have imagined a more difficult question to ask then global IP and trademark law. So I'll try to help. The first question is: Is the offendin

Wow... I couldn't have imagined a more difficult question to ask then global IP and trademark law. So I'll try to help. The first question is: Is the offending party in the same business as you? The goal of the law in dealing with trademarks is: "Will it cause confusion in the marketplace?" and "Is one party trying to benefit from the goodwill of the other party?" Those are the tests that a US court will apply to your case. If they are in the same business as you are. I would send them a notification letter of your use of the mark. Not a Cease and Desist. If you are in the UK you don't need to file a challenge to the USPTO, just a notice to the UK IP Office. Its the job of the petitioner at the USPTO to do a global search. In the end you can keep operating up until they sue you. They'd have to sue you in a UK court, which may be cost prohibitive for them... and at which point you'll have the evidence to show your use of the mark for the last 6 years and your notice to them of your use of it. Hope that helps...