Halstead Boiler Not Re-ignighting

[rvgledhill]

Hi.
We are having the odd cold day now so I decided to switch the CH on only to fid that the Boiler wasn't lighting. Its a few year old Halstead Buckingham III (conventional type). I checked the pilot light and it was out so followed instructions (on reverse of front cover) to re-ignight but does not.
When I press the pilot gas control button there is no sound of gas yet the piezo ignition switch seems to be clicking.
Any clues or suggestions on how to get it re-ignighted would be appretiated.
Many Thanks

Rob

 

[fitz1]

first job is to establish whether or not gas is present.