How much weight does a trademark actually have?

If you have been operating since 2005 using that name, you'd have protection by default (can't remember the exact terminology).

Especially if they're doing the same thing as you, they're impeding badly, using the exact same name.

However, if cavanlimos.com is not based in Ireland then forget about it.

If you have been operating to some extent, then you'd have a case.

If you haven't been operating at all and have no honest presence to be seen, they have probably gotten off-the-hook.

Hypothetically, you can't just buy up a company name and then never ever use it. You can do that with a website domain etc. but a true Business, there comes a time where they'd be the 'new' Cavan Limos.

It would depend on what the letter says. You have to be prepared to carry out any threats you make otherwise they won’t believe anything you say.

Depends if he has money. If he has, he may fight it, if not, he’ll cave.

You thrive or not by virtue of your customers - if you provide a good service, sell useful goods and have built up a good reputation and relationship with your customer base - then you likely have little to worry about. Word of mouth is still important here and even if a new customer stumbles on the other site, they'll figure quick enough that it's not the right place.

If you provide a poor service or poor goods though and have a dodgy reputation with some customers, then maybe more to be worried about.