Video caption says a compilation of Spifire formation flying at the IWM Duxford - certianly I can't recall more than 10 flying at any Legends display (plus a BBMF example or two).
Ah Legends... just over two months to go...
Lancman, certainly several Griffon Spits in there - I love that "urgent ripping snarl" as I've described it before.
JEM60, as I recall, one September Duxford display featured slightly more than 20 aircraft, mostly Spits and several Hurricanes. Was it the BBMF formation that arrived from behind the crowd?