Its a C3 chaps - really no immediate action required, by all means start putting money aside into a pot for an upgrade, but depending what else needs doing on the property, and how much free cash there is, if need be it can quite safely wait a few years or be done as part or the next round of major works.. There is something amusing about the upside down grey service head at the top left and the old style black loop feed unused at the bottom right, I assume this building has had serious work over the years ;-)

Mike.

What was the plastic off peak boards with no rcd protection coded ?

Gary

What can I do with a plastic consumer unit

Not sure, but the meter doesn't quite fit in with the tune of  'Up She Rises' !

C3 is fair and I don't think there is an easy way out. Besides wooden boards here and there, I would be more concerned about cables that go to consumers - these seem quite aged and may cause issues. All of these (I think it would be lighting and a corridor) are not in a trunk and are right against the wooden wall. I would check their rating against the fuse these are on and verify the tightness of all contacts.

Presumably C3, as would be expected - no RCD protection for cables buried in walls?