"progress" was not included on the original uk lp because it was the single a-side, and it was trade wisdom that british customers/fans resented singles being released on the albums (other than best ofs/greatest hitses), as they didn't want to pay twice for the same track. this chunk of "wisdom" definitely lasted well into 1967 in the uk record business, and prob'ly well beyond that...
quite whether cloggierecordfandom agreed, disagreed or was simply never consulted on the matter, this deponent knoweth not: nor how independent of fontana yuk-of-gb-and-norn-iron - or fontana.fr - fontana.nl may've been at the time - you'd've thought .nl would rule, given the parent philips is/was dutch, but - it seems not, leastways, not at that time.
This record came inside the jacket for The Pretty Things LP 687 341 TL so I do not have cover images to add. It differs in song selections only on the leadoff track which is "Progress" here, while it is "Road Runner" on the other LP.