Jim Gregory wrote:

It's called a 3-position single pole c/o (change-over) with centre off,
but such a beast is not made for standard single wall panels, [...]

It's available in the various grid systems though - e.g. MK part K4899
http://www.mkelectric.co.uk/products...5&rangeid=1026
(described as 2-way centre-off). This is easily built into a single
wall plate, or any other required combination.

--
Andy