You almost had me, then I got to the bit that said “off road”.Does anyone fancy a mixed-terrain ride down south?
It would start somewhere around Norbury, head to the North Downs following (very approximately NCN 21, then loop across to join NCN 20 and back towards Mitcham following the River Wandle.
Highlights would include Farthing Downs, crossing the M25 twice, Woldingham School, riding across a golf club (legitimately) and some lovely off-road bits. Most of the off-road is no worse than the Thames Path along by Hampton Court or Hammersmith, but there are some steep descents and climbs that do require some care. I rode it on 700 x 28c on a road bike with caliper brakes. I've also ridden it on a rigid mountain bike with slick tyres and discs. The only thing I'd suggest is to make sure that you are geared low enough for the Surrey Hills.
I've done the same ride about 4 times since lock-down begain and reckon it's an absolute cracking mix of terrain.
Total distance is about 42 miles.
Route here: https://cycle.travel/map/journey/156843
thanks - discovered recently that ava gardner lived for donkeys years and died very close to one of my regular pre-covid evening cultural trips by bike - and very close to your great film ride route.