It's unknown because Flight International artist - again - invented it.
Do you see in capture:
"The type of transport which may become widely accepted on medium-stage routes in a few years' time. With four highly efficient two-spool turbopropsof about 4,000 h.p. each, it should carry 90 passengers for about the same direct cost per mile as the present Viscount." any direct clue to aircraft manufacturer?
Hesham, don't post artists impressions with another thread name a-la 'Unknown airliner', 'Another Unknown Airliner' etc. Title '1954 Airliner Artist's concept from Flight International' is more appropriate.