BOAC were the original operator of the Hermes, in the early 1950s. Yes, it was a thoroughly unsatisfactory design and they got rid of them after just a few years. They mainly got used on shorter trips to East/West Africa. The tail-heavy aspect was never overcome and apparently they presented a curious nose-high view air-to-air. Alas the prototype was so unstable in this respect, compounded by a miscalculation of the elevator rigging, that it crashed on the maiden flight, killing among others Jamie Talbot, the Handley Page chief test pilot.
They were never looked on favourably by BOAC and were sold off to UK independents operating mainly long-haul military charters, a major business in the 1950s, to points such as Aden and Singapore. Such independents were not allowed foreign currency to buy US-built aircraft, so it was the Hermes or nothing. Airwork was one of these operators, along with Skyways and Britavia, and later Air Safaris.
Airwork got a licence to operate cargo services from London to New York in 1955 but had no suitable aircraft for regular transatlantic operation, so chartered Transocean DC-4s for the route. It never worked out and they gave it up after a few months. I am surprised they managed a passenger charter because that involved all sorts of further licences, but I wasn't there to see it and you were
The various Bristol Siddeley sleeve-valve radials were known for their smoke on startup, when controllers in the tower would joke about "LVPs for the next 10 minutes". The engine manufacturer had a long although abortive relationship with such engines, Armstrong Siddeley luxury cars in the 1930s having the same style of sleeve-valve engine (although not radials of course).
It would be unkind to call the Hermes just a version of the Handley Page Halifax bomber (which my father flew in WW2) with a pressurised fuselage, but that's basically what it was.
The operating period for Airwork's fleet was from February 1952 to late 1959. The fleet comprised seven aircraft G-AKFP, and G-ALDA/B/C/F/G/O. DB and DF were both lost in 1952 within months of introduction, AKFP was a replacement, itself lost in 1957, and DG its replacement that year, so there were never more than five at once, and mostly four.
The Wikipedia page on the Hermes is pretty straightforward.