Thank you so much for these replies. Well, that explains everything, I wonder what other solid childhood memories I have that are slightly, but significantly wrong. I do have a mint speccy 48k issue heading my way from ebay and my original MM casette tape waiting to test just to make sure;) I'm so sure it that darn sound was there! Off for a bit of Pacmanicminerman in the meantime.
Fantastic work. May I ask a quick question? I remember there being an object collection noise when I used to play this on my real spectrum back in the 80s, but I've never heard it on any emulator. I assumed this was some subtle hardware feature that was not emulated properly, but here you seem to have restored it. Was I right in thinking this noise was not emulated properly or did I have a different version of manic miner back then. Thank you!