Actually SQ announced the fourth daily into LHR before the QF-EK tie up. It started in September as a 77W, but will become an A380 from Northern Summer when SQ will have 2 A380s leaving within 90mins of each other for SINLHR.
SQ also announced the 4th daily PER and MEL, while upgrading ADL to year round 12 weekly from July.
Unfortunately or fortunately, SQ's aggressive ramping up of capacity was the main reason that the ACCC didn't see the QF-EK alliance as harmful. If SQ as the largest foreign carrier into Australia said oh we can't compete and we'll cut services, the ACCC would have thought twice. However, SIA and Scoot and Silk Air will soon operate over 130 services a week into Australia, which would more than placate the ACCC.