Well, it is all rather a long time ago! But it is quite probable that G-ALZZ operated some of Autair's Scheduled Services while still bearing the Skyways logo. At that time most of Autair's Scheduled Services were operated by HP Heralds. Almost certainly never operated G-ALZZ for Skyways out of Lympe being a grass airfield and rather too short for an AS57. Probably operated out of Gatwick. Incidentally the prototype operated off the grass at the manufacturer's airfield at Christchurch - Hampshire.
I've never heard mention of the Ambassador being under-powered. The Bristol Centaurus Engine being one of the most powerful of its kind. However at MTOW I would guess that it would need nothing less than a 6000ft runway. That said BKS operated Ambassadors out of Leeds Bradford (subsequently I am led to believe that this is incorrect and that their Ambassadors operated out of Newcastle and not Leeds) in the days when the runway there was considerably shorter than 6000ft. I believe BKS carried out weight saving modifications to their Ambassadors.But yes it would be interesting to obtain the opinion of somebody who has flown the beauty.
Autair routinely performed training and bi-annual checks on their pilots whilst operating the Saturday night newspaper run from Luton to Dublin. This would involve a single-engined approach, overshoot and landing at Dublin with two or three tons of newspapers on board.
However having just read Nick Corrie's Monograph on the Ambassador (Elizabethan Swansong) it would appear that apparently the aircraft could struggle to gain height if attempting a single-engined overshoot when very heavily loaded. At Dusseldorf on 8th April 1955 BEA's G-AMAB's port propeller slipped into reverse pitch shortly after takeoff. The engine was shut down and the aircraft returned in poor visibility for an emergency landing. Because the aircraft had not been properly aligned with the runway an overshoot was initiated but the fully loaded aircraft failed to climb and came down in a field a few miles away from the airfield. There was no fire and everyone survived. The cause of the initial malfunction was never discovered and as a result reverse pitch on the Ambassador was decommissioned.
https://aviation-safety.net/database...?id=19550408-0
I seem to remember that George Errington gave a spirited single-engined display at Farnborough in the early years of the AS57's development.