Perkin, it was everything you mention, and more!
Yes, I know! To add insult to injury, just as we approached the runway, 5th in line for take off, about 2.5hrs late by this stage, the captain pipes up to tell us that the runways have just been closed due to some rubbish blowing about...d'oh! Eurostar next time methinks...
Interestingly, I always seem to experience delays at LHR, but have flown to LGW a similar number of times over the last few years and have only once been delayed in the famous fog of Dec 2006. Have I just been lucky, or does LGW tend to be less delay prone than LHR? It always gives the impression of being a somewhat smoother operation.