The opening day of the first Glastonbury, 19th September 1970, coincided with my 2nd birthday - that's me hugging my mum - and being so young I don't remember anything about it. For the record I was also at the second event in 1971 which is when the Pyramid Stage first appeared.
My dad was a very keen amateur photographer and so we have quite a good record of both the 1970 and '71 events. Up until the late 60s Dad was shooting almost exclusively in black and white but around 1970 he moved to Kodak colour slide film which was relatively unusual. His colour photos of the '70 and '71 festivals are therefore a pretty unique record of these events (I don't think I've ever seen any other colour photos from 1970).
From what I understand from my dad's recollections, the '70 "Pilton Pop, Blues and Folk Festival", as it was originally known, was a bit of a non-event. The hippy jungle drums had spread word of the festival to London where my parents lived at the time. They drove to the festival in a VW Camper out of idle curiosity and the fact that it only cost £1 to get in. Perhaps as a further incentive Worthy Farm was also offering free milk to festival goers and one of the photos I'm sending shows my mum clutching her jug of milk in the completely empty field with the stage behind her. There's also a photo of a group of festival go-ers sitting around the burnt out wreck of a farm waggon which they used for a camp-fire. I believe Michael Eavis was rather cross about this vandalism of his farm implement! He's the person being interviewed, possibly by the BBC, in one of the 1970 photos. The experience can't have completely put my parents off because they returned for the second festival in 1971 - one of my favourite photos is of a hippy getting a ride in a tractor bucket (I'm in the background with my mum). My dad's photos of 1971 festival are more striking as the event was clearly a little bit bigger and the Pyramid Stage was a great focal point but it was still tiny compared to the current version