I went to turn off the mains water this evening to replace the cold tank ball valve and the valve was seized, so I put a block of wood between it and the kitchen cupboard and applied a bit of leverage and the stopcock top joint came off the feed pipe. Tried undoing the top connection and olive and putting it back together while getting soaked, but the pressure was too strong.

The spanner to turn to stopcock in the road is in the garage somewhere. A quick look and I can't see it anywhere.

Grabbed socket set thinking that will do, called at next door neighbours to see if he the road stopcock spanner to hand and no, so went into the road, where fortunately the water mains pipes and all of the valves have been replaced over the last month and found it is a plastic valve you can turn off by hand.

By this time I had about 0.5" flood in the kitchen, 0.25" in lounge dining room and about the same in the utility room and running under the connecting door into the garage.

Fortunately, the kitchen has a lino floor, the utility room ceramic tiles and the lounge dining room also has ceramic tiles with rugs (continental style), with only the edges of the rugs slightly wet, a wet dogs bed, so all cleared up with a couple of hours of mopping. It could have been far worse.

I took the internal stopcock off but it is seized solid, put it all back together and I will get a new valve tomorrow.
An important lesson is make sure you know where your stop valve is in the road and have a suitable spanner to hand, if required, before you start any plumbing.
