I have now found the file these images are from and as I suggested previously they actually prove that the idea of a dual launcher was rejected in early 1962. These were not even proper ship designs, rather they were illustrations produced to support a report into how the RN could install both stand-off ASW missiles and CF.299 into a single 3,000 ton hull (the culmination of this, HMS Bristol, was later described as being 6,500 tons to the treasury) to meet the requirements for a new frigate. The working party ultimately concluded the following:
"The working party has concluded that though an integrated common launcher system for A/S G.W and S.A.G.W is possible for the IKARA weapon (and might be with ASROC) the possible operational advantages are likely to be outweighed by the increase in space, duplication of equipment and wiring, increased weight and cost, and the increase in operating personnel. It is recommended that in the new frigate and within the stated Terms of Reference the A/S and A.A. handling and launching systems should accordingly be fitted as separate self-contained systems.
It is considered that though technically feasible there is not a good case for using the CF.299 launcher for IKARA in view of its greater complexity and cost and its complication of the loading arrangements."
In the multiple and large Ikara files in the National archives I have found no further reference to a dual launcher and no evidence of any further design, analysis or consideration of it. This early 1962 report seems to have been the beginning and end of the idea. However, what is clear is that there were, initially at least, plans for separate Ikara and CF.299 launcher designs for aircraft carriers and for frigates so it seems reasonable to think that the aircraft carrier versions of each launcher would have been in the 1962 escort cruiser design. The December 1962 decision to use the destroyer version of the CF.299 launcher in CVA-01 instead of a dedicated carrier version, which was cancelled, is possibly also the reason why the 1963 escort cruiser only had one CF.299 launcher too.
Consideration was also given to using the CF.299 tracking radar with Ikara but that was also rejected. And also pertinent to this thread; the treasury suggested that the Type 82 class (once its size and cost became apparent) should be regarded as cruisers whilst the Navy appears to have had its own internal debate about calling them frigates destroyers or whether to use the blanket term "escorts". All rather amusing for a design that started out as a 3,000 ton Leander follow-on.