For the time being, IOM companies have GB VAT numbers, and a banking system that integrates seamlessly with the UK one, as well as a postal system (quick, which country is 15 Hope Street, Douglas, IM1 1AQ, British Islands?). This makes the sales process to UK and EU companies painless.
So if you're a British citizen who's managed to convince HMRC you're not resident in the UK, this is a great way to pay very little tax. BUT WAIT, there's more!
If you _are_ resident in the UK, and a British citizen, but you can convince HMRC that you are in fact not _domiciled_ in the UK, you can pay HMRC £30,000 a year flat-tax, and only pay tax on the money you bring into the UK -- so if you keep it in IOM, or send it to Guernsey, it's tax-free, as long as you manage to avoid CFC regulations, which are left as an exercise for the reader.
None of this should be considered as tax advice, although if you genuinely don't live in the UK, and aren't anywhere else long enough to be resident (that DigiNomadLyfe), then the top three points should be of significant interest.
If you think the owner of the Daily Mail and similar glitterati[0] should be paying more tax than a Senior Developer in London, paragraph 4 needs some scrutiny.
[0] https://en.wikipedia.org/wiki/List_of_people_with_non-domici...