This legislation has been around since 2000. Do a search on IR35. It hit the IT contractors big time back then and it sounds like Customs and Excise have set their sites on Ryanair now. Brookfield pilots are disguised employees for Ryanair.
I can tell you from bitter experience that the Customs and Excise set the rules, change the rules on a whim, and then apply them back dated however they please. They don't forget about you, and are happy to hit you with a claim for, what they consider, 7 years unpaid tax.