I travelled on this bus on 23 March 2012 when it was still in Matjiesfontein and commented at the time that the poor bus needed to find time away from that harsh Karoo sun.
Topless Tours (yes the top was removed) was operating this bus, and is owned by its parent company CitySightseeing Cape Town, but there is no mention of current availability of the bus at all that I can see. The bus is still listed as registration CA5037 an AEC Regent III / Park Royal to Topless Tours in the latest Open Top Bus Site's Fleet List.
Strictly speaking the AEC Regent III was actually manufactured for use outside of London and for overseas markets so it is probably not a "London Bus" in the true sense of the words.
Watch Story Of The RT
A look at London's RT Buses, which graced it's streets from 1939 'til 1979.