Much longer flights have been done by VC10s since - I done more than one myself. In fact, I'm sure the VC10 still holds the record for a direct flight between London and Sydney.
Are you sure it was to Sydney? I have seen reports of a London - Perth non-stop by the RAF with 2 in-flight refuelings.
London-Sydney non-stop was flown by a QANTAS 747-400 on a delivery flight (without AAR!).