We have a fairly successful rose-selling website. On this website we have a rose care guide that was written by my late grandfather. We have records of this dating back on our website to 2002, using web.archive.org.
We have recently noticed another website which contains our rose care guide. The guide they show is a 90% match when comparing their current webpage with the version we displayed back at the end of the previous decade. At the current time, our website shows a much newer version of the guide, that has been updated a few times so is now only a 30% match, though we are still a bit annoyed at the using of our content.
We e-mailed the other company and got a rather snotty response back where they claimed that the content was actually theirs, not ours. However as I say, it's available on our website in earlier forms to the one they have stolen, and the writing style is that of my grandfather (he had this annoying habit of putting about three or four spaces after a full stop, something they have on their rose care guide but no where else on their website). In my e-mail to them, I told them we had traced it back to 2004 as that was as far back as I had been able to go at that point, and they claimed they had written it before 2004. What can we do beyond this point? Is that it was available on our site in 2002, but not shown on theirs for nearly a decade later enough proof that we wrote it?
The important question here probably isn't a question of law or evidence. Regarding the law, it looks like a clear case of copyright infringement; regarding the evidence, I suspect you would be able to put together a more persuasive case than the other business. Instead, the question is: what practical steps should you take to enforce the copyright?
You could refer the matter to a lawyer, but that would arguably be dispropotionate here.
A better approach, if you're willing to invest a little more time, would be to write to them saying that they must remove the material from their website by a specified deadline, and if they don't then you plan to issue a claim against them with the Intellectual Property Enterprise Court. You should read the relevant guidance and the practice direction on pre-action conduct before you send the letter (I haven't been involved in IP litigation for many years, so I'm not sure of the current pre-action requirements):
Please also treat this answer with care: there may be circumstances that I do not know about that would affect my suggestions here.