The thundersnow was something like this

http://news.bbc.co.uk/1/hi/uk/7864183.stm

but much louder and more intense.

You can see one of the towns Wind turbines being struck 3 times in around 20 sec.

http://www.thecourier.co.uk/News/Dundee/...-lightning.html

The thundersnow lasted around 12 hrs.

Apparently some light snow has fallen inside the M25 ring road around London and we are now beginning to see a National Emergency starting to take shape.