I suppose it is not as simple as all that (although a poor advertisement I grant you).
Part-time flypast pilots/crews vs full-time display pilots (and the associated rules) may be some of it, weather in the join-up area and along the route, and diversion fuel requirements back at a poor-weather base with fewer weekend divs as well I expect.
Weren't the Reds doing it out of Biggin (or at least into Biggin) - that probably helped.