"I can remember that around 1950(ish) there were some fairly big flying boats at Hythe, near Southampton, new in those days, I think, not sure if they had four or six engines? Can't find anything on Google so maybe it never entered passenger service."
Parabellum - as Kitwe says, the Saunders Roe Princes were laid up around the period you mention, but also at that time Aquila Airways were still in operation (ceased 1958);
Aquila Airways: Facts, Discussion Forum, and Encyclopedia Article
I can remember my Dad taking me to Southampton to see one of the big Cunard liners (QE or possibly QM) and an Aquila Sunderland (/) was taxiing - and he told me we had missed a trip to Kenya in something similar when he first went there in '54 (I believe it was by about 2 yrs)
PZU - Out of Africa (Retired)