September 1969
Concerto For Group And Orchestra  
People involved
Ritchie Blackmore (gtr); Ian Gillan (vcl); Roger Glover (bss); Jon Lord (org/pno/kbr); Ian Paice (drm); and the Royal Philharmonic Orchestra conducted by Malcolm Arnold.
Lord's Concerto was performed live at the Royal Albert Hall on 24 September 1969; it was televized (in the UK and Denmark) and later also released on video (slightly edited), and it gave Deep Purple a huge marketing. Gillan finished his lyrics just minutes before taking the mike; and a subsequent concert arranger secured a local brazz band to play with Deep Purple since he couldn't get the symphony orchestra! (Read all about it on the sleeve notes to the video.) The Concerto was also performed at the Hollywood Bowl in the US during August 1970. Any recordings from that?

Albums & singles
See the Deep Purple Discography