I mentioned this idea to an instructor at one of the clubs. This person told me that if I owned a US registered aircraft in the UK, I would only be permitted to fly it for six months in any year. This was plainly a lie.
Later, I learned that many UK flying instructors resent people going abroard for their training and resent people owning US registered aircraft in the UK. These people will tell you any old rubbish just to put you off.
Welcome to UK GA, BP
The one thing which never changes is the amount of disinformation and where it comes from.
Unfortunately many people "in the business" haven't got a clue so they probably actually believe it themselves, because they heard it in the pub.