Have an ancient Glow worm space saver boiler?

Boiler had been working ok, hubby saw slight soot build up. Has hoovered soot off (protecting pilot from dust) - pilot would not work.
New thermocouple fitted and took jet off and cleared of soot buildup.
Pilot lights smashing now, however will not stay on when switch is moved to pilot on. Keeps going out.
Any ideas as to what to try next?
Thanks the missis (in a warm caravan in the garden at the mo)