Press Association analysis of CAA punctuality figures found departures from the Bedfordshire airport were, on average, 20 minutes late last year.
Gatwick was the second least punctual at 19 minutes delays, along with Jersey and Durham Tees Valley. Birmingham and Bristol came in at 18 minutes and Belfast, Manchester and Stansted 17 minutes.
The ranking takes into account all scheduled and chartered flights from the 25 airports featured, but excludes cancelled flights.
The average delay was 15 minutes. Heathrow proved the best performing UK airport (11 minutes delay) following by Leeds Bradford, Belfast City and London City.
A spokesperson for the Airport Operators Association said the UK’s airspace infrastructure was “outdated” and called for modernisation.
