Michael Somerton-Rayner ('Summertime Reindeer' in my godfather's language) operated at least three JetRangers during the 70's to mid-80's and which were for some of that time accommodated upon a converted barge (or lighter) located at the end of Barge Street House (
west of Blackfriars Bridge) in front of what was commonly known as 'Oxo Tower Wharf'. The lighter was (so I have been told) named 'William' Barge and sometimes referred to as 'Barge William Heliport'.
The two 'Rayner Rangers' of recent interest, G-BAML and G-BAZN (the latter now wearing her DHL livery and being loaded prior to departure) upon Barge William in 1982
To horse! BAZN departs the lighter bound for 'Harry Heathers' (LHR)
To the best of my knowledge, those Rayner Rangers serving the DHL contract, carrying their cargo of priority letters and small parcels, used to land at the Holiday Inn at Heathrow.