On Sunday, 21 June 2015 23:20:25 UTC+1, Jim x321x wrote:
My house was built and wired in the 1980s and has an old-style fuse box.
The old fuses have all been repeplaced with cirquit-breakers plugged into
the fuse sockets.

There can be issues with doing this. Certain designs have gaps between the MCBs and the cover which would fail modern ingress protection rating against poking things in. Also the plug-in MCBs sometimes have a lower breaking capacity than 'conventional' MCBs.

For rental property electrics have to be 'safe' (and in Scotland from later this year, have an EICR - electrical condition report).

Given the age and current circuit arrangements it's likely that replacing the CU would be a fairly straightforward swap if the original wiring hasn't been buggered about with.

For renting you would also need mains powered interlinked smoke detectors.

Owain