Originally Posted by stut

Problem is, the road journey in from Gatwick is awful: frustratingly slow (and hence expensive) and unpredictable. I would only do this with particularly large luggage. If you can carry it, I'd get the train and then a taxi for the last hop inside London.

Depending on where you're headed in London, bear in mind there are other train services than the ones to Victoria - Thameslink will take you to London Bridge or to Blackfriars, City Thameslink, Farringdon and St Pancras. If this gets you closer to your final destination, it could be useful.