Why is winter still a shock to UK rail?

Once again I stand on a platform waiting for a train that is currently delayed and may yet be cancelled.

Because of poor rail conditions, that being a light frost this morning and a bit of light rain, the whole Southern rail network is suffering delays of up to 40 minutes. My own train is currently delayed by 24 minutes.

I’ve been travelling to work by train for most of my 20+ year working life and it seems that the onset of winter comes as a shock every year.

Seeing as rail technology hasn’t really advanced in the last 20 years, why is this still an issue? Same technology, same conditions, same problems.

Perhaps the problem is partly due to the old technology. Perhaps it’s due to trying to tackle the problems with methods that have never worked and surprisingly still don’t.

It’s OK though, I’ll keep paying the ever increasing rail fares.

Edit

A few hours after writing this, a train driver by the name of @SuburbanDriver sent a link that explains why leaves on the line can be such a problem:

[Link no longer exists]