In 1977 (or perhaps '78) Super VC10 G-ASGC (the one preserved at Duxford) crossed the Atlantic from New York to Prestwick in 5 hours 1 minute.
So far as I know this is still the fastest Atlantic crossing by a subsonic commercial airliner.
Highly unlikely, given that Air Canada fly St John's-Heathrow which is nearly 800nm shorter than JFK-PIK.