Mann's flew Mrs T from Chequers to Glyndbourne and afterwards back to Battersea in July 1980 in the Agusta 109A without any of that hoo-ha about aircraft security as far as I know, although one of her special branch did ask me if we had flown a "test run" before hand!
It was a bit of a squeeze for them all in the back and I am sure she had a much better flight to Harrogate in Lord Hanson's exec 76B fifteen years later.