I found this Douglas DC-6A/C (c/n 45531/1015) on my way in Alaska, as Tanker 51 with Conair, registered C-GIBS; the photo on my website triggered Bryan Benn to send me 2 photos of this "Six" doing commercial services in Europe, over 20 years ago...
This photo of HB-IBS with Balair of Switzerland was taken around 1981, and sees it on final approach to Runway 26 at London-Gatwick, UK.
Balair operated with this DC-6A next to a Fokker F.27 Friendship (HB-AAZ) and Douglas jets (2 DC-9s, 2 DC-8s and a DC-10).
HB-IBS was taken here a year before, in January 1980, as it ran it's engines up seconds before departing on Runway 08 at London-Gatwick.
Thanks Brian !
Background info on Douglas DC-6