Legendary British comic actor Frankie Howerd crossed paths with The Beatles numerous times, from early meetings in 1963 (see above) to Howerd's role in Help! as Sam Ahab (a scene cut from the final print). Frankie even portrayed Mean Mr. Mustard in the lamentable 1978 film Sgt. Pepper's Lonely Hearts Club Band.
In 1968, TV presenter David Frost was producing a series of specials designed for syndication in the US market. One such program was David Frost Presents... Frankie Howerd, which aired in February 1969. Paul McCartney participated in a segment of this show, taped June 16th, 1968. After a bit of banter with Frankie, Paul introduced one of the fledgling Apple label's newest signings, Mary Hopkin, who sang "House Of The Rising Sun".
The original videotape isn't circulating, but here is an off-air audio recording of the original broadcast: