The key signature for it is a single Sharp Sign, which I equate to the G Major Scale. I then work out that's all the white keys, except for the F key, which becomes F Sharp.Why? There isn't a single F Key used in the piece I'm looking at? Where's the purpose?!
Secondly about the same piece, it sounds wrong! I won't argue if it's written that way, but on the 4th measure (I think) where it's G A B, it should be A B C me thinks! All up one note to the previous measure.
The last thing you need to worry about is whether or not the notes in front of you can be trusted.
"tonic (I) and the dominant (V)" - This is intervals? Or inversions? I can't remember, but I havn't put the effort in to figure that stuff out yet, I think I will though, since so many people use the terms.
Thankyou for the super fast replies, especially this time of night! That answers all the London Bridge queries....