I don't know about JFK-LHR times (although I did fly it in a Super as a teenage pax in '67) but this seems quite impressive - courtesy of the Brize Norton website:
On the 8th April 1987 101 Squadron celebrated its 70th Anniversary by breaking its own non-stop speed record from UK to Australia. Wg Cdr Jim Uprichard flew a VC10 K3 from Brize Norton to Perth in just under 16 hours, refuelling twice in the air on the way.