How big is Glastonbury?

Glastonbury is underway. The gates opened earlier and the main music starts later in the week, with the three headliners on Friday, Saturday and Sunday. I visited the festival back in 2010.
How big is the site?
Geoffrey Prytherch has produced a useful mapping overlay to place anywhere you want to compare it with the size of the festival site.
Here it is overlaid on Ely.
I know those going this year will have an amazing time. It is an unforgettable experience.