normal fuses (in the fusebox) still have to be 16A (B or C class), the main fuse can be anything 32-50A or even tri-phase 50A.

>ring circuits up to 100m, cookers and electric showers up to 7200W

Normally those tend to be 3phases.

Of course it's possible to get over 16A on a single phase and a circuit breaker but that's quite a non-standard option. The issue is that if the fuse/circuit breaker is rated for 32A in a standard application (i.e. an outlet) the cables are likely to burn 1st.

I think we might be getting our wires crossed :)

I'm talking about the UK here, which I understood to be similar to the rest of Europe(?).

That's a UK website and 3 phase isn't common here. I've just double checked my fuse box, and I have a 32 amp fuse for my socket ring main.

Don't forget for a ring main the current is spread over 2 wires, so if theres 32amps power draw, theres only 16amp on each side of the ring.