On the link below, is found a photo which might illustrate a previously-unknown system used in the Bechuanaland Protectorate from the 1920s, possibly to 1935. No previous reports/photos are known, but the single ‘B’ could well have coded the territory name for all the few registered vehicles.
Any ideas?

B 141 could be the previously-unknown plate type for the Bechuanaland Protectorate (Botswana from 1966).. 1920s Dodge car.
http://www.flickr.com/photos/hannes_steyn/2210292102/in/set-72157603611718163/
The above B series was replaced by the BPx type, possibly in 1935, when the country was allocated BP as its International Identification code.

A Vauxhall Cresta BPD 162, seen in GB during 1969, carries the BP-prefixed white-on-black plates which ran from (possibly) 1935-1966, when the ‘P’ was dropped from the registration. (e.g BPD became BD). Brumby archive

BD 2198 .. This Hillman Avenger was photo’d in London in 1976, using the new (from about 1974) yellow plates, otherwise system unchanged. D=Gaberones, the capital. (The oval changed from BP to RB (Republic of Botswana) in 1967, then to BW in 2003.) Brumby archive
*************************NAMIBIA
Whilst in Southern Africa, some January 2015 photos of the first-noted Namibian vanity plate, were taken at Eland’s Bay, Western Cape.

The South-West Africa international oval which applied until independence from South Africa in 1990. NAM thereafter. Brumby archive
*************************SWAZILAND SNIPPETS

Another historic picture from the Southern African zone, is SD 6018 from the 1922-79 Swaziland series. This Mk1 Ford Cortina was photographed in Britain in the 1960s.
These plates were made for SD in ZA. Brumby archive

Seen in Cape Town in June 2015, a new series of Swaziland Government plates, emulating the South African red digits for state vehicles. Swazi plates have always been made for them by South African manufacturers. GSD is Swazi Govt. and PO is for the Police. Taken by Lester Day

A normal current Swazi plate type from the series commencing 2010, in which Q 795 B is the registration, SD the country i/d and M codes Manzini district. Expiry 2017 indicates that car tax covers more than a year,,,, Brumby archive 2015

The eccentric Swazi King Mswati runs a fleet of grand cars just as you would if you were left in charge of the nations’ wallet. Here is one of his vanity plates on his R-R Silver Spur. The central Lion sometimes faces left, sometimes right, possibly according to the political set of his ever-changing aid donors. anon

Windscreen-mounted tax discs are used in Swaziland by those who can afford them. The expression ‘Clearance Certificate’ is unusual. HSD 305 AM Brumby archive