Diana was a British girls' weekly comic published by DC Thomson from 23rd February 1963 through 4th December 1976. Hard cover annuals continued to be published beyond the date of the last weekly issue. Appearing to have been a regular Diana feature, the Man in Black was a version of the spooky storyteller host found in EC's horror comics of the 50s and Charlton's and DC's late 60s/early 70s horror titles. This 8 page story simply entitled "The Man in Black" is skillfully drawn, although the story is very simple with a rather weak plot. The artist, David Matysiak, was kindly identified by his daughter, Janet Matysiak.
I don't know exactly what to derive from this story in terms of lessons about 1970s Britain, except that, like some other British comics from the period, it seems to share some commonality with its American counterparts, in this case the storyteller being the regular feature in an otherwise varied horror story slot. It is true that the USA and Britain do really share a special relationship, one that has involved trans-Atlantic sharing of culture for quite some time, back to the roots of the USA as a nation, and this is just another small example of that.