This was the Mothers Milk tour that came to the UK two/three times in 1990 according to http://theside.free.fr/tour/tourHistory.php3
My first exposure to RHCP was buying the Knock Me Down 7" single from the discounted box on the floor in Stylus in Hastings in 1989 purely because I liked the name. That said I didn't like the track and promptly forgot about it. Fast forward to early 1990 when I saw Anthony and Flea interviewed on Raw Power which also showed video clips of the new single Higher Ground and Fight Like A Brave. I was really taken with their sense of humour, the energy in the music and the powerful mix of rock and funk. I was hooked. Mothers Milk had failed to chart and so wasn't available in any local shops so I wound up buying the CD on import from Tower Records in Piccadilly.
As for the gig... yes, well, uummmm. Nope, don't remember a thing about it - heaven knows I wish I did - not even who I went with, but I suspect my brother was there. It was probably good though, don't you think?
RHCP - Out in LA live at the Pinkpop Festival 1990