Hmm,
The problem with the RAF have with the multi-role potential is twofold. Firstly, we've seldom had any spare capacity as we've flogged the frames to death - often in the semi-strat role it wasn't meant for to paper over the failings in procurement and the supportability issues with other aging fleets. Secondly, the RAF hierarchy has always ignored the usefulness of multi-role large ac whenever they became a threat to FJ; AC130 or Harvest Hawk - might endanger Jag/Harrier/GR4 (as would the Nimrod if it had been allowed to drop wpns when based at Basra rather than rely on GR4s/Tankers etc miles away...). The irony is that we've lost the Jag/Harrier anyway and savaged the GR4 front line....Genius...
As for dedicated ASW, perhaps a non-starter, but as a multi-role LRMPA why not? Oh, perhaps BAES have a pod that'll fit on a Typhoon...