From 26 March 2017, Flybe will inherit the dormant slots at Heathrow for flights to and from Aberdeen and Edinburgh. The Exeter-based airline will challenge British Airways on those routes, and some test bookings suggest that fares are already falling as a result. But BA will have a distinct edge over the newcomer in terms of speed.

On the Edinburgh-Heathrow route, the quickest British Airways flight is 85 minutes, with the average journey scheduled for one-and-a-half hours. But all three daily Flybe services will take two hours. The fastest train between the Scottish and English capitals takes only four hours.

The distance between Edinburgh and Heathrow airports is 333 miles. The schedules published by airlines are “block times”, from pushing back at one airport to reaching the stand at the destination.

The actual flying time for a British Airways Airbus jet is less than an hour if no holding is required before landing at Heathrow, but slack is built in for queuing on the ground and “stacking” over the Home Counties waiting for a landing slot.

The aircraft that Flybe will use for the link is believed to be the Bombardier Dash 8 Q400, a propellor plane with a maximum cruising speed of 414mph — which the maker calls a “jet-like” speed. The top cruising speed of BA’s Airbus A320 is 533mph, about 30 per cent higher. But on a relatively short hop, aircraft are in the cruise for a short spell.

On the 403-mile trip from Aberdeen to Heathrow, Flybe is allowing two hours and 15 minutes, compared with as little as 90 minutes on BA.