Thanks Guy. Hadn't spotted that before! However, it does confirm what I keep telling FindMyPast, the houses of my grandparents and immediate neighbours are missing from the register.
As the transcriptions (and therefore the searchable index) is a transcription of what is actually on the register, it might be worth looking under abbreviations.
For instance, my father currently lives in a reasonably long road (c.250 houses). Most of those addresses are found under xxxxxx Crescent, my Dad's is under xxxxxx Cres and a few under xxxxxx C. So for Road try also Rd, for Street try Str or St, etc, etc, etc.
Might not help, but you never know.
Also, just because they don't appear on the search, doesn't mean they are "missing from the register", just missing from the index (or incorrectly indexed). I couldn't get my GGrandparents to appear, no matter what seach terms I put in. So I found some people up the street who did appear, then changed the Item number one up and/or down and sure enough one of them consistantly errored, because of bad indexing. I told FindMyPast, they checked and confirmed I was right) and 24-hours later they appeared using the same search criteria as used before.