The photo was taken at WOMAD 2007 (WOMUD as it became known), it was worse than any wet Glasto I've ever been to and I first started going there in 1989
Picture of my friends in 2007. Shows how deep it can get.
Like I said, drainage is better now, so I'd be surprised if it ever got that bad again.
Bonus image of random people:
Clearly neither of you went in 2005!!
I saw a guy paddling a kayak between the tents at one point (I didn't think to ask why he'd decided to bring a kayak, but I guess it paid off for him )