Done a wee.
 

All four tortoises have been hibernating in the Fridge at 5 degrees since Saturday. Did one of my checks today and three are fine eyes closed and responding to touch so pretty normal.

The fourth a 5 year old in good health. Was eyes open. On closer inspection he had managed to get the hibernation bedding wrapped round one of his feet pretty tied up he had also done a massive wee.

He's only been down since Saturday so do I over winter him, or put him back down in the fridge?

I'm tempted as early on to give him a few more days winding down with baths and try again on Saturday.

as he's only been down a few days I think I'd do as you suggested, get him up, a few more baths and try again, better to be safe than sorry, it has warmed up a bit is your fridge ok temp wise.

not down in Sussex it hasn't brrrrr Fridge in indoors and depending on the shelf is between 4.3 and 6.7 deg c

Just give him a cool bath (make sure you see him drink), dry him off and put him back in the fridge.
As I've always said brumination (hibernation) for tortoises is not a long winter sleep. It's just getting to cold to be able to do normal tortoise activities. So your tortoise will be awake during brumination.

Danny