British plugs and sockets
The British standard of plugs and sockets (BS 1363) is one of the safest ones in the world, having been designed in the 1940s with safety in mind and improved throughout the years. UK plugs have three rectangular pins, which since the 80s have to be sleeved to prevent anyone from coming in contact with them while they're live. They also have a built-in fuse (a unique feature) to protect the power cord of the appliance, necessary due to the 32A ring circuits often found in British homes.
Safety shutters have been present since the beginning, being one of the first countries to make them mandatory. These operate by having the earth pin - which is slightly longer - push down a plastic flap which normally covers up the line and neutral contacts. Because of this, an earth pin is mandatory, even on non-earthed appliances; these often have plugs with plastic earth pins, called ISODs (Insulated Shutter Opening Device) instead.
Aside from the UK, BS 1363 plugs have also been adopted in Ireland, Cyprus, Hong Kong, Malta and Saudi Arabia.
Standard double power socket
Rating: 13A 250V
Double-gang (or "twin") sockets, like the one shown here, are the most common type used in the UK and Ireland. A power switch is present for each outlet to cut power to it; while this is a popular feature, it's not an actual requirement, unlike in Australia or New Zealand. As this is a cheap model, the switch is single-pole, but on higher-end devices they tend to be double-pole to properly isolate the connected appliance.
The socket is a single-block item and so is mounted to the wall box using two screws visible from the front; small plastic covers are then placed on top in order to hide them. Wiring is done with screw terminals, which support both solid core and stranded wires. Screwless terminals are now available in the UK, though they're not yet common.
Single-gang socket
Rating: 13A 250V
This is a single power socket. Single-gang boxes tend to be used for light switches, but they are occasionally installed for outlets as well. Unlike the one shown previously, this particular example doesn't have a power switch.
One interesting feature present in all of these sockets is a metal bar connecting the earth terminal to one (or both) of the mounting screws. This is because metal wall boxes are quite common in the UK, and require being earthed for safety.
Shaver adaptor
Rating: 1A 250V
While the BS 1363 plug is the only type used domestically in the UK and Ireland, there is an exception: shavers. These use special 2-pin plugs designed for this purpose (BS 4573, an adaptation of the old non-earthed BS 372 standard) or Europlugs, meant to connect to a shaver socket inside a bathroom. However, ordinary British sockets aren't compatible with them.
This adaptor solves this problem, by safely allowing the connection of a BS 4573 plug, Europlug, or US two-pin non-polarised plug to a BS 1363 socket. To prevent them from being misused, strict safety regulations regulate the design of shaver adaptors: as such, they must be fitted with safety shutters and a 1A fuse and labelled as being for "shavers only".
