christep sorry, I thought Qantas did have an Atlantic crossing! Oh well, wrong again. ANZ certainly go from LHR-LAX; I don't know if any other non US/UK airlines fly from LHR-USA.
As far as I understand it, VS plans to operate two LHR-HKGs daily, with one going on to SYD - that, at least, was the last plan that I saw! If that's the case, I'd guess that the LHR-HKG-SYD will be the VS202, returning as the VS203.
SQ have certainly pressed for a crossing of their own, but I suspect they didn't want Virgin operating via Singapore to Oz, so they had no quid pro quo to offer. As they reap 49% of the profits of Virgin's operation, which is mainly transatlantic, I doubt they'll lose too much sleep over it!