The Lynx has always been capable of the aerobatics you talk about. It has only stopped if the routine didn't need it or the RTS wasn't signed (only happened once and such a fuss that they reversed the decision!).
The reason it can are
1 - bloody good pilots
2 - baffles in the engines so it doesn't go quiet (Navy don’t have them I believe?)
3 - Gallons of power in temperate climates.
4 - a good response from the public making the BEs want to keep doing it.
The fixed head makes it manoeuverable and capable (it wont chop its tail off as a flexible head would under -G forces)
The old Mk1 didn't have a lot of power so was less capable but the pilots did try their hardest!!!!!
Hope this helps.
