When the UK armed forces contracted in the late 70s and 80s there was a rush of great engineering personnel into civilian roles, about the same time the civilian companies reduced their apprentice intakes dramatically, in fact, some stopped recruiting completely.
There is now a shortage across the industry of suitably qualified and competent mechanics and engineers.
I've no idea what the pay rates are in the armed forces but a post apprenticeship mechanic can now expect between £40k and £50k. Licenced Engineers, almost double that.