Something else has just occurred to me...
From the front of the 1979 UK tour programme, it's clear that at the time of going to print, the artwork for String of Hits wasn't ready, since there was no mention of the album in the programme and the cover photo was the guitars against the Vox amp pic (which was very good). They did, however, get an A5 flyer printed and slipped them into the programmes at the last minute. So what? I hear you cry. Well, this illustrates how long it can take to get designs sorted out and finalised and stuff printed. Therefore, it seems reasonable to assume that they wouldn't want this to happen again, thus they got the artwork sorted out as soon as possible. That is a guess, but based on such evidence as there is.
Yes, it's clear that the recordings they made at Abbey Road in late '79 were originally intended for release in 1980 by EMI. EMI must have been confident that the Shadows would agree to their terms regarding the upcoming contract renewal and, conversely, the Shads must have been confident that EMI would agree to their terms. A shame that things didn't work out. I can now certainly see (or imagine) many or most of the tracks on Change of Address fitting into a String of Hits style album. And, again, it seems incredible to me that they were in the studio as late as July '79 and then back in again by October or November. Looking at the rec. dates that exist, this was highly unusual for the Shadows during the 1970s.
I guess we'll never know for sure what the title of the album might have been if it had been released by EMI... but I bet it wouldn't have been 'Change of Address'.