It isn't just engineers though!
In ATC a civvie (ie Sgt-Flt Lt) controller for NATS earns £80-£100k pa (plus a shift allowance of £15-£30k) and an assistant (SAC-Cpl equivalent) is £35-£60k)
SNCO level HR people in civvie street earn over £55k compared to the £40k ish the RAF pays.