nope it a seat and weight limit.
over 19 seats and or 10 tons, private or CAT they have to go through the full security process including liquids. Its not just a UK thing its EU wide.
The bigger FBO's have there own security arrangements which they can process them without the usual ball aches.
As for what happens after that I suspect nobody will want to say because in the UK anyway the DFT or who ever deals with it these days, will say its illegal for both crew and pax to have access to the security cleared hold baggage in flight.