The plane had developed a fault and was destined to be stuck at the airport for 8 hours awaiting the arrival of a UK based mechanic.
Instead of waiting for this, the passenger identified himself as a licensed mechanic with an affiliate of the airline, and was cleared to perform the maintenance work.
After a brief repair, the plane was on its way back home with just a 35 minute delay, instead of the 10 or 11 hours it would have taken if the plane was made to wait on the UK mechanic.
From now on, I’d like the airlines to load a mechanic on any of my flights, along with a doctor and a decent chef. The airline announced that they were “very grateful he was on the flight that day”. I’m sure the passengers share that sentiment.