TWO RONNIES - BLACK PIANIST SKETCH

Evening All!

Could someone please help me - I'm trying to find the Series/Episode that contained a musical sketch of Ronnie Barker made-up as a black jazz pianist/singer whose singing and piano playing becomes more and more enthusiastic as the song progresses (and his posterior doubles in size) - At the end, he is pounding the keys so hard that the piano collapses totally!

Thanks in anticipation,

KeithCEng