Assuming that we're talking about a wide-body, long-haul arrival, then even if we restrict it to flights originating from Africa there are 3 or 4 to choose from, all of which arrived some time before the reported discovery of the body at 07:55.
BBC now reporting that the body was found with Angolan currency.
While that doesn't necessarily imply that's where the flight originated, BAW76 from Luanda landed at 07:44 last Sunday morning.
BBC News - Heathrow flight death man 'possibly Angolan'