I'd never heard about the Avro 776 until now (I only have the "Fighters and Bombers 1933-1950" volume of "British Secret Projects") - and I'm intrigued! I do have in the documents an MPA proposed by DHBC based on the DHBC-5 Swan (HS.748 analogue), which was an in-house project conceived by DHBC as a "low cost" supplement to the Canadair Argus; it was ultimately not taken up by the RBCN FAA, and the single prototype had the ASW equipment removed and was taken on by the Royal BC Constabulary for the coastal patrol role. But now I'm intrigued by this idea. The Argus was retired in 1984, after which its function (previously shared with Vulcan B.2(MRR) and the DHBC-8 Merganser (BC-built Shin Meiwa US-1) was filled by the DHBC-8 alone. But now I'm wondering if perhaps Trident-based MP (and maybe AEW and ELINT) aircraft might not be a good idea.
These would all have to be rebuilt from civilian Tridents, as now that I've finally finished the complete DHBC serial numbers list the addition of new airframes to the list would entail entirely too much work - unless I reassign some of the c/ns to these military variants: from the first Bluebird to the last Kehloke DHBC built 3,270 aircraft, this number is set in stone! *unless*... I suppose I could add numbers in the late 1980s/early 1990s: after 1987 there were only Kehlokes built, and there wouldn't be too much to change in the numbering, if we add a few built in 1991-1993. This also gets me wondering about the effects of the sale of DHBC to Boeing on these military Tridents; I wonder if Boeing would've been alright with the Trident's type certificates going to Supermarine as a condition of the sale... well I suppose they'll have to be. I doubt Supermarine would build any new complete Tridents, but they'd then be responsible for supporting the existing ones, keeping that function in BC, which is an important consideration for a military type...
Off the cuff I'm thinking the Trident 7D would be the best option: about 39 m long (precise length not yet determined: for the record, my Trident drawings are all done to a scale of 1 pixel per inch), max 147Y, longest range of all the Trident variants at 2,500 nmi, and powered with the RB141-4, built from 1972 to 1983: ideal range in time for looking at replacements for the Argus as the land-based MPA, and still deep in the Cold War, and I'm sure MOD (and APTO in general) would be quite happy to have an ELINT/EW variant of the Trident to fly out of RBCAF Uwenpet on Iturup... if we replace the Argus on a 1-for-1 basis with the Trident MPA that's 8... up that to 10 or 12, add 4 or 6 ELINT/EW versions, maybe sell a couple of the latter to ROCAF (or arrange like the NATO E-3s with Luxembourg, and give the APTO ones to HK)... 14 can easily be arranged (PWAL and IDAL each lose 3 in 1979, CP Air loses 6 in 1981-83, Western loses 2 in 1982)... some AEW ones could be rebuilt from second-hand airframes later, zero-houred by Supermarine?
Okay, I think I have something to work with here!
As an aside, I have another idea swimming in my head - not even as far as a name yet - for a replacement for the Spitfire II: a multinational project (BC [Supermarine]/Japan [Kawasaki]/Primoria [Sukhoi-Komsomolsk] and others, maybe South Korea, Australia, UK?) for a 6th-gen VTOL fighter, probably with both manned and unmanned variants...