Good point Chris. The RAF Pageant at Hendon began in the mid 1920's, with other 'airshows' before and after, around the UK, but I'm sure there must have been others before these, around the World. I think, in the UK, the first 'proper' airshows after WW2 were the 'Battle of Britain' shows, originally at a number of RAF airfields around the UK on the same day, the nearest Saturday to September 16th, starting AFAIK, around 1950. But again, I'm sure there must have been others, especially in the USA.