It's a benefit of being on the outside that I don't have to bang my head against steel bulkheads and HMT's doors. So I am happy to pontificate without responsiblity.
Merlin? Or do you mean small helicopter?
The RN philosphy has always been the ship's flight is part of the weapons fit but that relies on the ships sensors and communications being up to snuff. We moved on from flags, semaphore and Aldis lamps, and the world has now moved on from voice so surely a small ship's helicopter need to be networked with sensors that provide an ASW picture or has to be able to provide its own.
The French Lynx HAS2/4 (FN) had it, as did the Germans and Dutch among other operators, the RN ones had various MAD fits. The export version of the Wildcat is offered with active dipping sonar. My point is as bought Wildcat has no detection kit, isn't networked so can't share the tactical picture visually when operated from an ASW roled ship, and in some cases is being operated off lone ships without a decent sonar fit. In a world of stealthy submarines and UUVs/AUVs 'we haven't done it before so aren't going to now' doesn't make sense to me (it never did). The crew need to be sure they know with a high degree of probibilty the location and depth of the target before dropping Sting Ray or depth charges, the era of NDBs is long gone. Sadly, history shows we have to lose ships and sailors before change happens (if the
San Luis had been luckier maybe it would already have).
The choice is between and ASuW helicopter in Wildcat and an ASW one in Merlin. If there was a proper ASW role fit availavble for RN Wildcat then a T23 could carry a mixed purpose flight but can't carry a Merlin and a Wildcat. MH-60R anyone? Sorry, no 'British Jobs' and HMG ain't paying to develop an equivalent, because they deem the risk is not high enough to justify the cost.