Luckily noticed before I left home so jumped on the Thameslink that leaves Hassocks 7 minutes before my usual train and made my connection at Gatwick (the Thameslink train gets overtaken by the GA at Haywards Heath normally).
I was only thinking yesterday that it’s been pretty reliable recently!
Derailment is near Victoria apparently so only impacting platforms 9-13 (including the Gatwick Express which isn't running). Most others should be more or less 'normal' (whatever that means for Southern Fail)
I only travel from Moulsecoomb to Brighton every day, but the first thing I do is check if the trains are running OK, yet the amount of regular London commuters that don't bother to check before they leave home always astounds me.
I was chatting to someone I regularly see in the morning and she had no idea, and another person on the train overheard and asked what was happening, when I told them they said "no point trying then I may as well go home", well if they checked the app they would have been aware and not bothered in the first place.