@Setanta,
Oh well....he's missing out on a good bit of informative chit chat.
My Nan, as a girl, worked in one of the Lancashire Cotton Mills and every one of the factory girls wore clogs.
The factory clog had a wooden sole, as opposed to the "irons" worn by outdoor workers.
Wooden soles didn't spark. Some of those old Cotton Mills were full of fibrous dust, and a simple spark could cause a major fire.
Here is a photo of a factory in Burnley at around that time......if you look closely at the women in the front, you can just about make out their clogs.
Also, in the background, there are some paper Christmas decorations. That big fold out origami type bell (just behind the tall lad in the middle with the flat cap) is identical to the Christmas decs from my childhood.
Like my Nan used to say "If things don't change, they'll remain the same."