What was the largest UK concert crowd ever?

Isle of Wight, 26 - 28 August 1970. Jimi Hendrix, The Who, ELP, Miles Davies. - circa 500,000.

Mainland UK: Knebworth Saturday 21st 1976. Rolling Stones, 10cc, Lynyrd Skynyrd, Todd Rundgren's Utopia, Hot Tuna and the Don Harrison Band. Around 350,000 people.