I understood that Mountbatten told the Australians they could have 5 Buccaneers for 1 TSR2. The Aussies never had any interest in the Buccaneer, but decidided that if even Mountbatten was against TSR2 it was obviousy going to be cancelled so they had better order F111's.
The reason the government wanted to cancel TSR2 may have been pressure from the USA who wanted to export F111's and rightly regarded the TSR2 as serious competition.