Ringi
They're the high earners and as such will get clobbered under the new tax regime. I can't remember the numbers but the principle is:
1. They go part time, and so stay under the high earners threshold. Yes they'll take a hit in pay but on the other hand they get more time off, so in effect they're not working for the Tax man.
2. Those that move abroad may be able reduce their exposure in part to UK Tax.