The older fuse boxes will take either wire or cartridge fuse holders and even MCB's with the correct adaptor plate, although I believe the front of the cover that should be fitted should be removed when fitting MCB's.
We have two such unit's (albeit larger) made of what must be Bakelite or similar although one is redundant as it was for the n longer fitted storage heaters/off peak electricity. I believe that whilst they are frowned upon as they do not feature any RCD protection they are very much still allowed.
My gran also has two such units one would be original and one a later addition, one is 4 way and one two way that seems to just do the Kitchen sockets and probably the shower. Note that the extra fuse box also powers a double socket in the dining room below a hatch where there used to be a door into the kitchen, there's a reason why I know that, and it wasn't on purpose!