Does my gas fitter know what he is talking about?

If the thermocouple is on it's way out, the slightest draught near the pilot flame will be sufficient for the thermocouple to shut down the gas valve.
Your engineer is probably right and the thermocouple will gradually get worse as the weeks go by.
Universal fitting thermocouples don't cost much, ave.£15 + 30 mins to fit and test. Lets hope your engineer gives you a fair price for the job

Cledlyn
February 2009