According to
mab01uk @ totalMINI.com these photos are of the two 1957 experimental Mini prototypes built and used for testing. He says:
They were nicknamed "Orange Boxes" disguised with Austin A35 grilles and mainly tested at night. The under bonnet photos clearly show the 950cc A-Series engine mounted the opposite way round to later production Minis, reasons for the change were given as carburettor icing and weak A35 gearbox syncro problems. The changes required the addition of a third drop or idler gear and also changed the cooling fan from sucking air in, to pushing air out into the other front wheel arch more efficiently. The 950cc engine was also reduced to 850cc to keep top speed down relative to the early braking power available at the time!
The battery was up front but was later of course moved to the boot. . . .