Re: pond pumps .. are they usually 230V? Only ones i've come across have been 12 or 24V with the transformer located inside.
There are plenty of low-voltage types available here too, but also many 230V submersible versions.
Outdoor outlets with the locking/sealing ring were also once common in Britain, and are still available. I think I have an old BS546 type kicking around somewhere. I'll post a photo later.
Paul, Regarding that weatherproof socket-outlet, are you required to have an isolator on that, as well?. What is the IP rating of that plug/socket arrangement?.
The only straight BS plug I've ever seen! Hereoutdoor receptacles are usually IP 54 IIRC. They have a spring loaded lid that forms a "roof" over the plug when in use. I think they are not rated for permanent use. Personally I'droute such cords inside through a piece of conduit. All circuits have to be RCD-protected at the panel,so it doesn't matter whether indoor or outdoor receptacle. If possible outdoor receptacles are located on balconies,porches etc.
They're IP66 rated, and no isolator is required. The Lewden types pictured are still quite acceptable, although generally only for commercial environments as the BS546 types have no shutters, and of course protection against the elements when a plug is removed depends upon somebody screwing the cap back on.