The microlight was a camera ship for Concorde, at the request of the Concorde pilot Capt Mark Jealous, who is a flexwing student pilot.
The microlight was flown by his CFI and both were sharing a frequency for some planned air to air shots, but unfortuantely cloud scuppered the plans.
The flexwing microlight that was used is a 100mph machine and the open cockpit would have given some spectacular footage, had Wx been better.
I'm sure the commercials didn't mind waiting a couple of minutes