yeah IP55 BS1363 sockets are "weatherproof" they've a waterproof cover over the socket it usually closes tightly over the plug when in use too.
Most of these outlets on the market here have their own RCD built in.
However, since the regulations and guidelines only recomend the use of the "industrial" type socket for outdoor stuff any electrical contractor installing the BS1363 variety is open to massive law suit if someone gets shocked by one.
From the ECTI :
Q: Are there special plugs and sockets for outdoor installations and if so why?
A: Yes. We like most mainland Europe countries do not consider indoor plugs to be suitable for outdoor installations subject to weather and rough handling and so ordinary 13A sockets to I.S. 401 are not suitable for outdoor use. Like all socket outlets up to 32A, they should be protected by an RCD. The Rules require that outdoor sockets and industrial sockets comply with IS/EN60309 standard. In this system both the plug and socket are hard wearing and are deemed to be suitable for outdoor use. The single phase plug is coloured blue and the socket is inclined towards the ground to prevent the ingress of moisture. They may be more cumbersome than the flat pin plug system but they are safer.
