I take a couple of long plaids with me when off in the camper van and wear them much like the NCO in Figheadair's post.

They are useful if there is a brisk breeze as they stop the draught and keep the pleats from flying, but having been caught out once in a bad storm I was able to wind the plaid around over the kilt, then up over my head. I was soaked to the skin with water running off me, but wet wool is not cold - the fibres actually swell and make the fabric more windproof.
Half way back to the van I stopped to watch a couple of badgers playing in the water running down the gutters, so quite a memorable evening.

Back at the van I stripped off and wrapped myself in a great kilt before hanging up the wet things and drying my hair in a towel, still just fine and warm.

Next day I realised a lot of people had abandoned the festival due to the weather, but I had to make my way home last Friday in a similar storm, and I only had a man made fibre fleece blanket to put over my woollen coat - I got very cold. When I reached home I put on the great kilt which has been repurposed into a full length dressing gown for winter wear.

Several decades have passed since the storm with the badgers, so I am considerably older, but I am sure that I would have been less affected by the weather last Friday if I'd had two layers of wool rather than just one.

Anne the Pleater