Another Reason You may find drum brakes on a Cooper is Back When Cooper S Brakes Were
A little harder to Find and more expensive than They are Now,
With the COOPER brakes parts like disc rotas drive flanges disc pads etc
were at different times very hard to get and sometimes expensive so people took the cheaper
option I have seen that done many times

_________________
" A Hundred Years From Now It will not Matter what my Bank Acount Was,
The Sort Of House I Lived in, Or The Kind Of Car I drove ... But The World May Be A Better Place
Because I was Once Important In The Life Of A Child"

My Cooper (well, former Cooper by the time I bought it!) had twin lead drums when I bought it, I was the one who threw the 7" discs back on. And back then (1999), a single 7" rotor from the respected Mini businesses in Padstow was worth about $175! As the King rightly says, parts weren't cheap!