Thanks for this Hawk777 , so it seems that despite the hopes of many on here, BA have not been able to obtain any waiver (or similar) to allow pax to stay onboard in SIN if they need to get from LHR to SYD or visa versa.

I very much doubt that both BA11 and BA15 will keep running as it is now only Singaporeans returning to Singapore and SQ is offering (supposedly, but in practice BA is cheaper!) discounted fares to repatriate Singaporeans. I know that BA11 was every other day and BA15 was still every day. I doubt that will last much longer.