I've gone round this corner hundreds of times, and probably dozens of times in the wet. This time I hit the white line and went splat. Part of the problem was a recent change in inner tube, to a big thick thorn-proof one. It's more rigid and I think that - plus being freshly pumped up - made it a lot less grippy in the wet.
Anyway I escaped with only a few bruises/scapes and a broken bar end luckily. So kids, stay off the white lines in the wet!
(the irony of the big "caution" sign is not lost on me - although I'd prefer that Brisbane City Council spent a bit more money and straightened out this little chicane, because I've always found it quite dangerous, and it's only a matter of time until somebody gets badly hurt there)