I knew the chap who signed for the refuel; he had 'taken over' the already in-progress refuel so that others could go to lunch.
In a cruel twist of fate, the presence of the Stn Cdr on board ensured a priority take-off for the Basset, at what was a very busy airfield in the Gnat/Hunter era. There was just enough Avgas in the fuel feed system to get airborne - a more protracted hold before take-off may have revealed the problem. As posted by Krystal, the Swiss Cheese was well aligned that day.
HB