“One reason that Merlin's payload if more modest than the Chinook's is that it is built to modern standards of crashworthiness”.
Not wrong, but why compare Merlin with Chinook in the first place?
Am I correct in saying the RN first selected Merlin? They envisaged two roles from day 1. Primary – ASW, replacing SK5 and SK6. Secondary – Commando, augmenting, not replacing, SK4. This is 20+ years ago, but I recall the specifics hadn’t been thrashed out as to whether all (103!!) cabs would be ASW and a proportion supplied with role mods to convert, or whether some would be non-ASW from the start. I suspect the latter – the detail of the role mods was being worked out (in 1985!) and the time to convert was horrendous.
The RAF requirement came along later and that is where I believe the politics kicked in, not least because the RN buy was decreasing rapidly with every passing LTC round. Industry (not just Westland) had been encouraged to plan for 103 and, unusually, had been allowed to publish this detail. In simple terms, the MoD didn’t look too good when it cut the RN, so people viewed RAF Merlin as a political expediency to allow them to say the total Merlin buy was pretty close (or at least closer) to the original provision. I may not be wholly correct, but I'm not too far out.