Interesting point! It is noteworthy that two of the best songs (ITILYTM, When it Comes) on the NHB tour were not on the album, possibly deliberately saved for a later album
"proof" of that is that the NHB arrangement for Calling Elvis seems to be a mix between the original idea (that was a rockabilly) and the OES album version.
Another song that suffer a BIG change was Fade To Black. As mentioned by MK himself, this song was planned to be another rockabilly style.
Maybe the idea for a secong NHB album was a 'all original songs' instead the first one that was a 'cover album'
Maybe, Ed pushed Mark enought to transform it on the next Straits album.
Maybe, maybe, by contract, Mark needed to release another Straits album. He had the songs, so... why not?
Maybe...