Several blogs here cover Horsenden Hill, including its magnificent west meadow. It is an ecologically unique and precious wildlife resource in west London. So the idea of up to 15,000 people entering the meadow to have a music festival does not bear thinking about.
A petition to stop this is gathering momentum; https://www.change.org/p/stop-ealing-council-and-junction-2-music-festival-from-destroying-horsenden-meadows If you care about Horsenden Hill, do please go and sign the petition. And try to think of anything else that you can do to challenge this event.
The petition is now closed, and is announcing SUCCESS. Councillor Deirdre Costigan is quoted as saying that the event will not go ahead at this venue.