I hadn’t seen it documented anywhere before Paul Murphy’s post. Looks awfully likely to me.
Totally agree with you on the lettering; that’s why I clumsily described it as “screw-hole”.
What really impresses is the sheer volume of work during this period. I remember opening the pages of the music press and being absolutely bowled over on a weekly basis since his work seemed to be everywhere; on the reviews pages and then the ads as well. If you bought singles and albums and went to gigs as voraciously as I did, it felt like you were surrounded…but in a good way.

Is it documented anywhere that BB had seen the Left Book Club graphic before this? Seems like it might be coincidence to me. He made subliminal faces all the time (Tommy the Talking Toolbox is another) so the Blockhead design was almost inevitable.

Another point which I don’t think I’ve seen mentioned elsewhere–and this is a supposition of my own–concerns the album title lettering. Each character has holes in it because they’re meant to resemble those letters you’d buy in DIY shops to attach to a garden gate or the front of a house.