Advertised in Gramophone May 1968, where it is stated to be "this month's fourth release" in the Beecham Legacy series. Appears to have originally been released with the black label - Discogs has that, and a later red label repressing similar to this one, though it says "EMI Records Ltd" on the label circumference, making that a 1973 or later pressing, so the pressing here is probably very early 70s.
Beecham describes how he would end a concert with a 'tranquiliser' as an encore, to calm the audience after a stirring climax to the programme and send them home happy
I find the Saint Saens Bacchanale to be a delightful 'Lollipop' which calms to an Arabian serenity, then climaxes to a whirling frenzy, after which you couldn't shout for any more.