Having worked at DASC (formally IFS) I concur with Courtney Mil. When many of of these 'vintage jets' were in RAF squadron service display flying was carried out by pilots who were experienced operators on type and had extra hours to practise their display. If I remember correctly any display flying had to be approved by a VSO normally the AOC at the beginning of the season. Most of these aircraft have some nasty little foibles which which could catch out experienced combat ready pilots when exploring the flight envelope. Even the humble Chipmunk had to be treated with respect. We all really enjoy watching these vintage jets flying but they were designed in the 40's, 50's and 60's when swept wing aircraft were very much cutting edge.