1974 Bucolic Frolic - July 20th. Allman Brothers/Van Morrison/Doobie Brothers/Mahavishnu Orchestra/Sensational Alex Harvey Band/Tim Buckley. 60,000 fans. The Allman Brothers stage included - 700db-25,000 Watt Sound System-equal to the noise of 7 low flying aircraft ! 2x fifty foot scaffolding towers with multi-coloured lights. There were 30 arrests.
1975 - July 5th. Pink Floyd/Steve Miller/Captain Beefheart/Roy Harper/Linda Lewis/Monty Python/John Peel(DJ). 40,000 fans. Pink Floyd's stage included fireworks, lights, a screen, a giant stage 15ft above the crowd, 13.4 metres high & 15.2m wide. And with the band's PA plus 3 other 2 1/2 kilowatt PA towers.
1976 August 21st. The Rolling Stones/10cc/Hot Tuna/Lynyrd Skynyrd/Todd Rundgren's Utopia/Don Harrison. 100,000 fans. Paul & Linda McCartney turned up to watch.
1978 A Midsummer Night Dream - June 24th. Genesis/Jefferson Airplane/Tom Petty & the Heartbreakers/Devo/Brand X/ Atlanta Rhythm Section/Nicky Horne(DJ). 60,000 fans. Introduced by Bob Harris(DJ), Genesis' stage included mirrors, lights, laser beams, fireworks and a 200ft stage.
1978 September 9th. Frank Zappa/The Tubes(who closed the show)/Peter Gabriel/Dave Edmunds/Boomtown Rats/Rock Pile/Wilco Johnson's Solid Senders. 40,000 fans. The Tubes set included props, smoke, a car driven on stage, and then finished with a tribute to Keith Moon who had died earlier that week.
1979 August 4th. Led Zeppelin/Todd Rungren & Utopia/Southside Johnny & the Ashbury Dukes/The New Commander Cody Band/Fairport Convention. August 11th (minus Fairport/but including The New Barbarians/Chas & Dave). Some sources report 93,000(4th August) up to 200,000 fans, possibly over both weekends. Led Zeppelin's stage cost £50,000, it was bigger than the previous years - the biggest ! There were 150 back stage crew. Led Zeppelin's fee was rumoured to be the largest ever for a concert. David Lytton Cobbold was fined for exceeding the midnight curfew by the Council. In that years annual 'Sounds' readers poll, Led Zeppelin at Knebworth was voted No.1 Live Gig.
1980 June 21st. Beach Boys/Mike Oldfield/Elkie Brooks/Lindersfarne/The Blues Band/Special Guest Santana. 43,000 fans. It cost £500,000(half a million pounds !) to stage the concert. During Santana's set 5,000 ping pong balls were dropped from 2x B17 Flying Fortress bomber planes, there were 2x dog fighter planes, and some parachutists.
1981/82 Capital Jazz - July 25th/26th transplanted from London, with Chuck Berry amongst others. 11,500 fans over both days. July 17/18/24/25 featured 40 bands including BB King/Ray Charles/Art Blakey.
1982/83 Greenbelt - 20,000 over 4 days, with a sunday afternoon BBC TV broadcast. The second included Cliff Richard on 1 of the 4 days, for which a license for over 15,000 was obtained.
1985 June 22nd. The Return Of The Knebworth Fayre - Deep Purple/Scorpions/Meat Loaf/UFO/Black Foot/Mountain/Mama's Boys/Alaska. Despite U2 playing Milton Keynes Bowl the same day(Billy Bragg on the bill played a bit of 'Smoke On The Water'), and the Glastonbury Festival the same weekend as well, 75,000 fans were at Knebworth. The Malboro Jets Aerobatics Team were hired to fly over, there were some parachutists, Deep Purple used £10,000 of pyrotechnics, a stage the size of a football pitch, 3 levels of PA, 4 levels of mixing desk, 6 lasers, 250,000 Watts, they had planned to play at 120db but had to keep to the legal limit of 90db because of the Council officials. Also there was rain & mud !!!(I was there). BBC Radio 1 broadcast on the day from Knebworth, and a recording the following weekend, and 6 hours called 'Knebworth Through The Night' in October. Chrissy Lytton Cobbold finished her book 'The Knebworth Rock Festivals', November 1985, published by Omnibus. It featured on the front cover, a live photo of Ritchie Blackmore from Knebworth(center), with smaller photos of Robert Plant, Phil Collins, Jagger & Wood, and Fee Waybill(The Tubes). In Kerrang! magazine's annual readers poll Knebworth was voted 'Best Live Gig', even ahead of 'Live Aid'. Deep Purple released their performance(minus 2 missing tracks), as 'In The Absence Of Pink - Knebworth '85', a few years later on Connoisseur Collection.
1986 August 9th. Queen/Status Quo/Big Country/Belouis Some. 120,000 fans, of which 1, sadly, was stabbed to death.
1990 June 30th. Nordoff Robbins charity concert. Paul McCartney/Pink Floyd/the 'super grouping' of Eric Clapton/Elton John/Mark Knopfler/Genesis/Robert Plant(with Jimmy Page)/Status Quo/Cliff Richard & the Shadows/Tears For Fears. 120,000 fans. An album of edited highlights from the event was released 'Knebworth-The Album', which reached No.1 in the UK Compilation Album Charts in 1990. Also 'Knebworth-The Event' Volumes 1,2,3, on video were released by Castle in 1990.
1992 August 2nd. 90,000 fans. Genesis/Lisa Stansfield/Runrig/Saw Doctors. Genesis had announced 2 concerts at Knebworth, but cancelled the second. There was also a BBC Radio 1 broadcast on the day.
1996 August 10/11th. Oasis/Kular Shaker/Prodigy/Manic Street Preachers/Charlatans. 250,000 fans over the 2 concerts. There had been 2.5 million applications for tickets !!! Also it rained.
2003 August 1/2/3. Robbie Williams/Moby/The Darkness/Ash/Kelly Osbourne. 375,000 fans over the 3 concerts. And there was a 3.5 million TV/Online audience. Robbie Williams released his performance as 'Live At Knebworth', on Chrysalis, which reached No.2 in the UK Album Charts in 2003.
2009/10/11 Sonisphere Festival. Including Metallica/Linkin' Park, then Alice Cooper/Iron Maiden, then Metallica/Motorhead, and lots of others over all 3 years festivals. Next 2012 lined up for July.
Thanks to Chrissy Lytton Cobbald's 'Knebworth Rock Festivals', and a few contemporary articles from 'Sounds' and Kerrang!, and the Complete Book of British Charts published by Omnibus, and also Wikipedia.