However, Wikipedia suggests [1] (the primary source is unreachable for me) that "the headline does not, however, appear in The Times Digital Archive, which includes every day's newspaper from 1785 into the 21st century. It is found in a letter published in The Guardian in 1978. [2]"

[1] https://en.wikipedia.org/wiki/Michael_Foot#In_popular_cultur...

[2] https://www.newspapers.com/clip/39001580/foot_heads_arms_bod...