Popping and banging

[Captaintremendous]

If it is obvious while the car is static (ie engine running on the driveway) then pull each HT lead in turn until you find the cylinder which isn't making a difference. Narrows down the location.

Tried it this afternoon and looks as though number six could be the culprit. I'm going to stick a new set of plugs in anyway as it won't do any harm and will be one more item eliminated.See what transpires then. Can't do anything till Monday as I'm in London, but will post results once done.

[911hillclimber]

Bit late now, but I meant the fault suddenly appeared after the run, ie like something has suddenly broken, cracked etc rather than a long time to slowly degrade.
I've has probs with corrosion in the plug caps...

Check the simple to do stuff first.

[Captaintremendous]

Gents.
Problem now solved. Turns out that a new set of plugs was the answer. I used NGK BR8EIX Iridium plugs and it has made a world of difference. I can only think that one or more of the old plugs was degrading in some way, so working fine under load but not otherwise.
Anyway, thanks for all the useful suggestions and feedback, much appreciated.

[911hillclimber]

Excellent, we all learn from each other's experiences.