This is a bit OT for the original question but the idea of 13A socket-outlets on DC is interesting and I think I need to re-read the standards.
I recall, rightly or wrongly, that they were anticipated for AC only from the outset and this was expressly stated in the revised title of BS1363:1950. There were switched variants from the early days of production; I think the idea of BS2814 was to combine desirable features from current commercial offerings, which were usually of a proprietary size and shape (as were BS546 products) into a standard configuration to make them physically and functionally interchangeable, more than to enshrine the use of a switch.
There have been BS1363 socket-outlets made with quick-break switches suitable for DC, by Wandsworth amongst others, however I suspect this was mainly to use the same tried and tested switch components and give the same apparent certainty of action as with other fittings in their range. In any case, reliance on the switch for DC breaking would require interlocking, and these fittings were not interlocked.
Shutters were designed-in to the BS1363 standard as a measure against accidental contact especially by children poking things into the socket, however similar shutters had been used previously as an arc quenching measure on socket-outlets for DC. Whether they recieved any consideration for that purpose within BS1363 I do not know.