Uncle Peter wrote

Anyone turn the pilot light of their boiler or gas fire off in summer?

It struck me it would cost a lot of gas over the year (and from what I've
read it's anything from £25 to £90 a year).

Then I found this! "With the pilot off, there are still trace amounts of
gas molecules in the burner and pilot tubes of your fireplace. The gas
companies add a chemical called Mercaptan to the gas which gives it that
lovely odor we all know. Spiders are attracted to the smell of the
Mercaptan and will sometimes build webs in the pilot and burner tubes when
the flow of gas is off. So when you go to turn on your fireplace in the
early fall or late summer, it will not work, and you will have to call you
local installer to come service the unit. This will cost money."

Doesn't explain how modern systems that have no
pilot light at all manage to work fine when first used
after the summer has ended.