FYI, the 5 in the number is actually an S.

Hi..
My late grandfather was a massive hoarder of old car memorabilia.. when he passed away he gifted me hundreds of old car log books, ranging from 1920s Austin’s, Crossley, Essex etc right up to the newer 1970/80s Minis Fords and so on.
I’m no expert on these but have painstakingly put them in order of makes and models..
The Mini ones are pretty straightforward as in description.. but one is bugging me and wanted to know if anyone has heard of another.
It’s a 1964 Austin Mini estate 850cc all pretty straightforward.. but the chassis number starts CA257 which relates to a cooper ??‍??.

Is there a special build for a estate that incorporated a cooper chassis, someone was sure that there was a small number issued for the South African police force can anyone confirm this.

Thanks in advance.