Under what record label was the Rolling Stones album featuring the song "Heart of Stone" released by in the UK?
Heart of Stone (The Rolling Stones song):  It was not released in the United Kingdom until featuring on the "Out of Our Heads" UK album released September 1965. Out of Our Heads:  It was released in 1965 through London Records in the US on 30 July 1965 (in both mono—catalogue number LL3429; and in stereo—PS429), and Decca Records in the UK on 24 September 1965 (mono—LK 4733; stereo—SKL 4733), with significant track listing differences between territories.
Decca Records