What is up with my boiler - a Potterton Flamingo 40?

I have a Potterton Flamingo 40 boiler in the house that we have literally just moved into. It has worked for a few days but the pilot light has gone out and I can't get it restarted, I've tried following instructions on the casing but when I release the grey twist around knob it just goes out. Anyone know if I'm doing something wrong, or if there are common faults with these boilers that are easily sorted? I had considered just replacing it before the fault anyway as its pretty old - might this be better than trying to get it fixed?