Went to do cold first, there was a lead pipe out the ground with stopcock looking like it feed the cloakroom/utility room alone with a really handy rain valve just above it. Turn it off, open valve water comes out... water comes out.. 10lts of water out... ok - its not stopping - just a trickle 0.5lt a min. , open stopcock, gushes as expected, go outside, turn off mains to house.. same trickle, turn on stopcock still a trickle. I couldn't stop it.

Figure ok - lets look at hot - into airing - close gate valve to cylinder, drain taps.. trickle - same as cold. close of riser to tank, drain tank.. still a trickle.

Took many attempts to finally get a solder on the cold T, just wouldn't drain with the drainvalve open too.

The hot I left the taps open and just cut the pipe where I wanted and cut again to throw a service valve on, got soaked but least I could solder after.

Not nice.. I'm thinking maybe a burst pipe forcing just enough water up the pipes but hot and cold?

I couldn't get into the loft space to see what was happening there, thats why the riser had a valve in the airing.

Thinking about this overnight, I was at the house last month to clean the washing machine drain, turned out it was heavely silted up, I ran a snake down it and pulled out what i could, at the time I couldnt identify the silt, thick heavy fine sand, grey without smell, and talking to the custard they have a lot of silt in the water after a main burst up the road.

I had to cut into the same waste further down and the cross section is 1/4 full of this silt.

I'm thinking it has to be a burst pipe sucking in silt, but unless its burst both their's and also on the main I cant see how the taps still tricckle after the mains in off at the road.