I've found BS546 2 and 5Amp used here for low voltage DC applications on boats in Ireland.

Typically 12 or 24V DC

I always think it's rather dangerous to suggest that tourists should bring BS546 adaptors to Ireland as the system is rarely used for normal 230V power sockets. You could end up plugging into a lighting circuit which could even be dimmed, low voltage DC etc.

I don't like the use of BS546 lighting sockets in hotel rooms for that reason. You're quite likely to have someone attempt to use an adaptor or even push a europlug into the outlet (they fit in the 5A variety normally used for lamps)

I far prefer the use of the "klik" system

[Linked Image from tlc-direct.co.uk]

and although it looks like it might, I don't think it mates with NEMA [Linked Image]