JimK wrote:

Oh and "forget" to finish the bonding to kitchen sink copper
pipework, after threading 20m of single through a difficult crawl
space, then test "everything" & sign it all off.....

A few years ago when I re-did my kitchen, I was hacking off some plaster
and encountered a solitary earth cable running across a wall, it was
heading towards the water stopcock via a 6' gap where the kitchen
extension had been build - I chipped away enough to confirm that yep,
angle grinder clean through the cable at both ends, presumably the
builders retrieved and "hid" the middle section of cable to avoid any
awkward questions ... thankfully it wasn't difficult to find another
route under stairs, across the landing and down by the soil stack to
reach the stopcock.