Which would appear to suggest that there needs to be a sustainment / force increase buy of Merlin. Latest FOIA info on total vs forward fleets dated Feb 2018, suggest the following :Correct, HC4 is not able to conduct the Crowsnest role.
But HC4s being used from LHD will dilute the numbers available for QEC and add further pressure on the small HMA fleet.
I won't mention Crowsnest!
Merlin HMA 2 30 aircraft of which 20 in fwd fleet (~66%)
Merlin HC 3/4 25 aircraft of which 11 in fwd (distorted by HC4/4A upgrade)
Puma HC2 23 aircraft of which 15 in fwd (~65%)
Chinook HC 4/5/6 60 aircraft of which 39 in fwd (65%)
Assume for a minute that the Merlin HC force will hit a 65% forward/total value and you've got 16 frames for a total of 36 Merlin frames in the forward fleet. From which you've got to give 824NAS around 4 frames for training / continuity, 814NAS at least 6, leaving only 10 frames for 820/849 to do pinging and bagging. You can probably get another 6 from 845 to do lift/HDS aboard QEC, leaving 10 for 846 to cover training/continuity and the "traditional" CHF tasking. That's eyewatering for the HMA fleet and tight for the overall Merlin fleet, if Merlin had a good serviceability record. If.......
I'm sure SHF can help out with their Wokkas, but it does seem that the FAA is a tad short in comparative terms. That analysis above shows that each CSG deployment could soak up over half the forward fleet.
It would be interesting to understand where the SHF cabs are committed, because - and not intended in a derogatory way - it seems there's a disparity in demand, noting of course that everyone wants a Wokka when they're in the poo. Seems a little strange then that a new Chinook buy is being contemplated - although I'm sure that's more to recapitalise the older cabs.