Spur of the moment, pure fantasy.
Nice easy back story, Australia develops its independent nuclear deterrent instead of the real world policy of engaging the UK and the US in the region, initially V-Bombers, then B-58. The failed joint Blue Steel project saw the B-58 life extended and supplemented with FB-111A, the planned B-1A, intended to replace the B-58, was cancelled leading Australia to lobby the US for Trident and six modified Ohio Class SSBNs. Of course once the B-1B project is kicked off Australia orders 24+12 of a modified version capable of conventional missions and cuts the Ohio order to four.
Almost ended very badly with the fin top disappearing into the carpet monster, luckily it was recovered and there was no need to suspend building.