According to Paul Pelletier's RCA discography this is a September 1966 release. The notes to this record state that the demo copy is dated 23/5/66 suggesting that it was delayed until September. There is no actual image of the demo copy on the site but there is a pic of the demo on the YouTube link although the month is partially obscured by the large A. Had the record been intended for a May release it would surely have been numbered below 1520 and not 1542 which is in advance of where the RCA catalogue no.s had reached by that time. Taking all that into account I think the release date of this single should be changed to September '66.
Kirkby is a suburb of Liverpool and as you surmise J23 of the M6 is the Liverpool turnoff. This junction linked into the A580, more commonly known as the East Lancs Road, which in those early motorway days was the main road between Liverpool and Manchester.
That's really interesting - I always loved Michael Angelo, wondered who 23rd were. Would you like to add a link back to here from DM 150?
In 1967 the only motorway with a Junction 23 would be the A1(M) and J23 would IIRC be near Bishop Auckland, latterly J60. I assume the band was from around those parts..?