I'd say this was probably the cause ... maybe with a tyre that didn't have enough grip for the conditions.

Towards the end of last summer I was riding with Vittoria Voyager Hypers, we were heading down to get the ferry across the estuary and I suddenly realised I was heading the wrong way and turned sharply when it was wet and the whole bike slid sideways ... the miracle was I didn't actually come off ... did leave a stain in my pants though

I had a 2nd incident similar a couple of days later so swapped out the tyres for ones better suited to the winter / wetter conditions.