Playing Wasting my Young Years - London Gramar with both hands at the correct key

All B, E, A, D are flat since the key is B flat minor 3rd with major 6th. This scale or key is called B flat Dorian.


One can play for example with the left hand playing higher than the middle of the piano keyboard:
F A B D (all notes together)
F A B D
F A B D
F A B D
B E G
B E G
B E G
B E G
F A B D
F A B D
F A B D
F A B D
F A C E
F A C E
F A C E
F A C E
B E G
B E G
B E G


while playing with the right hand in double high octaves the beautiful melody:
D C E C A
G
F G A
etc


But how are those harmony or chord notes derived?


It is much easier than it looks.


The bass number code is:


B7
E
B7
E
B7
E
B7
F7
E


So all needed is to use the 1 3 5 7 9 etc rule of possible notes above bass.
Remembering all B, E, A, D are flat.
Then choosing which of those notes to use simultaneously (using all of them is too much)
Then rearranging their order so that the music principle of least note change between chord implementation or voicing is used.


It is also worth noting that these 3 bass notes chosen by the composer are: B (the tonic), E (the subdominant), F (the dominant). Ie the tonic, subdominan, dominant of the scale B flat Dorian.


See also:


Bach Bass Rules - Bach, Niedt - PDF



Next day addition:
Another nice way to play:


A simple one is to play with left hand B D F and then B E G.


Another more involved way, nice sounding together with melody on the right hand is to play with left hand descending arpeggio D B F D B F D B E B G E B G E B ...


In this way bass code is D6, E, ... , F7, ... is followed.


This can be a nice addition to the colored scoring Melody Mystery Book or whatever it can be called.