The London-Sydney Marathon was a trans-continental road event and the 100 entries set off from Crystal Palace in London on 24th November 1968. The first stage was a 7,000 mile dash to Bombay (Mumbai) in India, before transferring by boat for the 3,000 mile journey from Perth to Sydney, arriving on 17th December. Fifty-six cars finished.

BMC entered four cars with the 1800 chosen for strength, spaciousness and proven rally record. The specially prepared 1800s included a tuned engine, reinforced suspension, perspex windows and aluminium bonnet, boot and door panels.

All four 1800s survived the Marathon. This car, crewed by Paddy Hopkirk, Tony Nash and Alec Poole, finished second, six minutes behind the winning Hillman Hunter.