Combination boiler plugged into a double electric socket

I have noticed that the combination boiler is plugged into the kitchen double socket. This has been like that for years but I have only noticed it as the double socket has become loose so it needs to be re-fixed.

I don't go around looking at boiler sockets as a norm but I would say that this looks unusual? Shouldn't the boiler have its own socket inside the boiler cupboard? The kitchen socket is just outside the boiler cupboard.