National Research Institutions explored high payload/range supersonics for military application. There were funds nowhere for solely-commercial applications. Engine longevity and structures-in-heat improved to permit USAF 8/52 to fund (to be) Convair B-58. In UK, RAE settled on the (Meteor-esque) layout funded 1953 as Bristol T.188 proof vehicle for 1954-funded Avro 730 recce/bomber, off metallurgy-industry novel tools for stainless steel. USSR and Dassault settled on alloy/M.2.2 for M-50 Bounder (flew 1957) and Mirage IV (flew 6/59).
RAE's Supersonic Transport Aircraft Committee sat languidly 1957-61 as just one among many such Advisory talk-shops (Swept Wing, Boundary Layer Control, Gas Turbine Collaboration...) It did not concern itself with what was to be transported - ASMs, recce pallets, other military loads, people.
By 10/8/61: UK had changed its mind on "Europe" and knocked on the door of the Club of Rome; France wanted a longer range Super-Mirage IV; USSR wanted a practical Bounder; US funded (to be) B-70, 10/61. So, off we all went - military, not civil.
UK 11/64 tried to chop (to be) Concorde, but 29/11/62 Memorandum of Understanding (Govts., as sovereigns, do not enter mundane "contracts") had included no break clause - a UK inspiration to prevent CDG lifting all precious UK lifeblood Intellectual Property (?!!?) in Project Week One, then decamping over the hills. So, onwards, now solely-civil as UK and France had chosen to replace/supplement deep penetration Air with FBMs.
USAF 1964 funding for Very Heavy structure, Very Big Fans (to be C-5A/TF39) could have/should have caused UK/France to abandon Concorde, but: Dr. A.Russell (BAC Technical Director), A Span of Wings, Airlife, 1992, P.178: “In one respect Concorde bore straight comparison to (T.167 Brabazon) - no questions from anywhere had been asked on comparative airline operating costs.” "A good example of how a Govt. can find itself supporting a glamorous scientific break-through which does not make commercial sense.” Defence, and Treasury Minister D.Healey,The Time of My Life, Penguin, 1990, P328. Big fans permitted Singapore Airlines to schedule to Heathrow about the same but dramatically cheaper on 747/PW JT9D-7Q as on its brief Concorde experiment.