I just noticed on the radar screen this Continental 777 flying from Bush Intercontinental to Heathrow. It’s a regular CO route, but this one doesn’t seem to be a regularly scheduled flight.
1971 is not shown in their schedule nor is 1970 or 1972 as a return flight. It could be either an extra flight, a charter, or one that was added when it was thought BA would be on strike.
edit: looking further, this flight will arrive in London a little after 2AM, certainly not on a regular schedule.
Unlike other major airlines in the USA, Continental uses 19xx flight numbers for charters and extra sections.
Always look at the flight history for flights like this. You’ll notice for 1971 the previous flights were on 18 Dec from MCO to IAH and 22 Nov from FRA (EDDF) to EWR. In other words, no patterns to the flights. This is quite often a sign that the flight is a non-scheduled flight.