Just a few ideas of some things I'd like to see change in current British wiring practice. All very much my personal opinion, of course. In no particular order:

1. Let's specify dedicated branches for washers, dryers, and dishwashers. With a typical 3kW loading for each, I feel that piling them all onto ring circuits (often all on one!) is not the best approach. The regs. have always specified a dedicated 15A branch for a 3kW water heater. People often expect to be able to use washers, dryers, etc. simultaneously these days, so it's time they followed suit.

2. Let's abandon the ring circuit altogether. Any reasons given for its adoption in the late 1940s are no longer valid, if indeed they ever were, due to changing patterns of usage.

With the heavy stuff moved onto dedicated branches, wiring several radial circuits of 20A for general-purpose outlets would be fine. It would also make for easier servicing than in homes where receptacles are all on one or two circuits. And it would eliminate the possibility of overloaded cables due to an open ring (whether by fault or incompetent DIY).

3. We should abandon the "no sockets in the bathroom" stance. Let's allow a suitably placed receptacle, protected by a GFI of 30mA or less.

People WANT to use blow-dryers etc. in there, and will find a way to do so.
They can't run them on the low-VA isolated shaver socket, so they'll run an extension cord to a hall or bedroom, which may well have no GFI protection whatsoever. Better to provide a suitably protected outlet in the first place.

4. We should introduce U.S.-style clamps for terminating our equivalent of Romex at fixture boxes. The current technique of using a conduit knock-out just fitted with a rubber grommet doesn't provide enough protection against straining the internal connections.

5. The color code should be straightened out (or to be more precise, it should never have been messed up in 1970). We know what to expect of course, but it's quite illogical for blue in a fixed cable to be a phase and blue in a flexible cord to be neutral, for example. (Er, or was this system wired prior to 1970, in which case blue in a cord is hot after all!).

6. We really should use deeper boxes in many places. The prevalence of brick walls here is a big factor, but the common 1/2-inch for a switch and 1-inch for sockets just doesn't leave room for extra cables to be added later. (And frankly, is barely adequate for the originals.) I'd like to see 1 and 1-1/2 inch minimum respectively (or 25 and 38 mm as they insist on calling them now).

8. While we're on that subject, can we please tell the dictatorial EU bureaucrats to take a running jump and change all the metric specifications back to units that 99% of Brits are comfortable with.

That's probably enough for now. Any comments?