Well in my case, I meant it was turning the engine. Sounded perfectly fine except it just wouldn't fire. Battery kept it turning well for a good few minutes worth of cranking. 750CCA, so it cranked hard. No loss of cranking power with all that cranking, and no real voltage drop whilst cranking. After checking this that and the other (even around the fuel filler in case I'd ticked someone off and there were traces of sugar or something), disconnected the battery in case it was a computer glitch that might reset. Maybe that was it.
Took a bit more cranking, but eventually fired up and has been fine since, not a hint of trouble starting. Actually starts really well apart from that one time. Just thinking that maybe I just didn't have a good connection on the battery terminal (can't remember if I tightened up the other end of the earth strap too when I disconnected the batt). But the cranking power makes me think that was fine. I was pretty good at narrowing down what the issue was in the VN causing non-starting, but this had me stumped. 3 things to check: air, fuel and spark. So I was pretty confident I had fuel (heard the pump and after a while could smell it, sort of like a flooded engine), and with no issue cranking and new plugs that was a low priority suspect, but with individual coils that was going to take a bit to figure what could cause all of them to fail at once (apart from fuses which I checked with a multimeter, and swapping relays). Which left air. Filter and MAF looked fine on visual inspection. So all I could guess was computer (or security) being the issue. As I only had one key (and am unsure of how the security works - I thought if it was the key it wouldn't even try to crank) I just kept trying by holding the starter on overriding the autocrank (trying not to keep it on too long, in case).
So all in all I'm not that worried anymore, as it hasn't happened again since. And without the problem occurring anymore, can I even figure out what it was? MAF and TB needed a clean since, so that's why I suggested that it might have had something to do with it, but who can tell now.
Anyway, I appreciate the input, as I may need it if this ever happens again, but more trying to give info on my experience as well to add to BigBoss'. Such a similar sounding issue, maybe dud fuel wasn't my problem either. Might help someone else, even if I never find out. Oh and yeah I have had the battery checked since (well I was told it was done during the last service) on a proper machine. But if it's like the tester we used to use at the mechanics I worked at (not as a mechanic), that takes a while. So I wouldn't be surprised if the pricks didn't do a proper load test, let alone a full test (from memory it took like 20min to run). I'm already not taking my car back there for other reasons.
