We were away for the night yesterday and came back to a horrible fishy smell emanating from the downstairs cloakroom. Both loo and basin appear to be running freely through the outside manhole cover. Any suggestions. We have concrete floors.

Snif around the lavatory drain. Is the smell stronger there? Let me know. Tom

So sorry not to have replied before, Tom, but have been away again. We read through previous correspondence, some of which referred to electric lights overheating, and realised we had left the cloakroom light on while we were away. It was in fact this that had caused the problem. Many thanks for your help.
Nig

Thanks for the update. Tom