On 25/05/2021 12:52, Steve Walker wrote:
On 25/05/2021 12:04, Harry Bloomfield wrote:

Perhaps a bit of plumbing or heating - a copper gas pipe looks
identical to a water pipe.

Possibly, although it's easy enough to identify in many houses - with
gas coming straight through the wall to the meter and then from there
usually only going to the living-room fire, the cooker in the kitchen
and the boiler (often in the kitchen), with the latter two often a
single run. No gas upstairs and, in a house with suspended floors, the
route of each pipe downstairs can be clearly seen.

Our family house (early 60's) has gas entering garage then emerging the
other side of the dining room from kitchen floor but in the "wrong"
place so it goes around 2 walls surface mounted behind cupboards and
under sink to boiler.
My Brother mistakenly presumed it was cold water feed and cut into it to
put an outside tap in the garden.
Presumably if one then failed to fully isolate the supply (old rusty
isolation valve perhaps) and fired up a blow-torch to repair the pipe...