In article . com,
"DavidW" writes:

The gas exploding is another matter which I have no intention of
fiddling with! Though the pilot light does seem a bit small when viewed

That can certainly be a cause, although I have no experience
of that boiler. If it's not catching the gas as soon as it
comes out of the main burner, an explosive mixture can build
up before it finds the pilot light.

throught the window, Is it possible to turn this up a bit?

If it's shrunk or changed shape, it needs cleaning. It could
well be an indication that the whole boiler needs a clean, as
if dirt is building up, it will probably be affecting the
main burners too. This is extremely important if that boiler
isn't room-sealed. The pilot probabably has a gas adjustment,
but you mustn't adjust it until after cleaning the pilot
jet/burner (and it probably won't be necessary then).

When it's alight, what to the main burner flames look like
(if you can see them)?

Hints and suggestions are definitely welcome, particularly on fault
finding, as we don't relish the idea of a cold house on Christmas day!!

--
Andrew Gabriel