Thanks Paul,

The only reference to this standard when I entered it into Google, was at the BSA store where they mention that the BS546 standard replaced it.

Chronomedia's website mentions in their July
1947 entry that the BS1363 standard replaced seven round pin plugs.

http://www.terramedia.co.uk/Chronomedia/years/1947.htm

If you count the grounded and ungrounded versions of the common 2/5/15A plugs, that's 6. Must be a seventh discontinued one I never heard about.

Just curious.

Gene