DFC
Most airfields in the UK don't have what could be described as a fence, so walking in would be a lot easier and cheaper than flying in
Actually you can drive a car in the UK, with false plates, no road tax and no insurance, for as long as you can, so long as you don't get into any incidents and only ever park in a garage.
All these "security risks" are irrelevant when one considers that somebody who wants to commit a crime isn't going to worry about having FM immune avionics, for example.
Flap40
If you have 10 planes that fly IFR, and another 100 that only ever fly on really nice sunny days, most CFITs would be in the former group. Apart from a CFIT, it is hard to get killed in a plane - most landing accidents for example are not fatal.