G-AMPY was a longstanding member of the Air Atlantique fleet operated out of Coventry. It's still around and airworthy, currently in RAF colours with it's WW2 RAF number here:
(it seems links to Facebok are suppressed, but if you click Quote on this post I think you will see the link)
Like most such aircraft, it seems to be airworthy about 50% of the time, it was certainly around last year. It's been in Britain all its life, from WW2 with the RAF and then with a range of other operators. Air Atlantique was run by enthusiasts and have got several mentions from me here in the past - the DC6B painted up in British Eagle colours they brought into London City some years ago and then did a flying display at an airshow there was them !
The Northwest colours were in 1986, painted up at Northwest expense for their 60th anniversary. At that time Northwest seemed to have plenty of advertising and PR funds available right here in London, they were certainly trying to position themselves up against Pan Am and TWA. The DC3 was left in their colours for a couple of years afterwards, it got used for various commercial and airshow tasks in the meantime.
I wonder if the various photographs and film were used in the USA. The US tail number is obviously bogus. You could imagine them doing this with a Minneapolis operator, less so one in London.
This I think is the classic shot of it during its time, taken at London Gatwick in 1986 !