Andy Hall wrote:

It can make a great deal of sense.

For example:

- The pump may be broken or on its way out

- There could be a partial blockage in the heat exchanger or elsewhere
in the system.

If the temperature rises quickly enough, the overheat sensing can trip.

However - back to the original point of it cutting off the pilot.

Either way, if the OP is not sure about what he is doing, he should
seek the help of a professional.

Sound advice. The boiler may have a thermocouple which is linked to the
overheat stat, hence when it overheats it cuts the pilot. The overheat
stat may have gone sensitive but is an important safety device. Are
there Trv's on all of the radiators so when the rooms are warm there is
no where for the heat to go? Is the pump failing and cannot get the
heat away from the boiler. A temporaray fix may be to turn the boiler
stat down so that the water temp is reduced and hopefully will not trip
the overheat stat. It may just keep you going until you can get an
engineer in.

Legin