Southern only acknowledged at 12:25 on their own website that there was a problem:
Line problem.
Train services on all routes are being disrupted due to poor weather conditions earlier.Short notice alterations, cancellations and delays of up to 60 minutes can be expected.
I cycled in this morning (after last week's misery I couldn't face another week on the train). Decision had been made over the weekend, and after seeing colleagues arriving in my office 1/2/more hours late, I am definitely glad I did it.