On Sunday, 1 November 2020 16:21:21 UTC, ARW wrote:
Just a tip on buying a new one Dave. Try to get one to BS7288:2016 and
not old stock that is to BS7288:1990.

The old stock is possibly better as it doesn't require additional protection upstream of the RCD socket.

The later standard requires upstream protection. I don't know if the socket itself has changed.

BS7288 has been omitted from the 18th Edition Wiring Regulations for providing RCD protection to sockets. It's an issue of some discussion on the IET forums.

Owain