UK What kind of socket

[G.walter]

My appartment building has hallway plugs with a different fitting to every day plug sockets - it's the same as a normal uk plug socket except the distance between the top hole and bottom two is considerably shorter. What kind of socket is it?

 

[westward10]

Can you show a picture of it.

 

[snowhead]

Presumably designed to stop people plugging normal electrical appliances in.
Over the years there have been plenty of specials, it may be something from the past.

 

[Mike Johnson]

It's a special plug for use by the landlord to clean the hallway with their equipment, but prevent residents for running their homes on it.

 

[ipf]

Is it a 'clean earth' socket, T shaped pin?

 

[James]

Undoubtedly so tenants can’t plug things into them.
Here is a link to the many different types

13a non-standard uk plug - Recherche Google