Compose a piece of music that follows both the given musical theme and the letter-based structure provided.
X:1
L:1/4
M:6/4
K:G
['B B', 'F/ E/ F/', 'E G']  
X:1
L:1/4
M:6/4
K:G
 E | E B B (B A) B | G A G (F A) F | (D F) A (A G) A | d3 z2 G/A/ | B B B e d e | 
 (B3/2 c/) B/A/ (G F E | A G A B2) e | d B G F A F | E3 z3 |[M:6/8][K:Bb] F/ | c c/ c/B/c/ | 
 A/c/G/ _E F/ | B B/ B/A/B/ | (c3/2 c) c/4d/4 | e/d/c/ c d/4e/4 | f3/2 F F/ | G/F/E/ B/A/B/ | 
 c3/2 c F/4F/4 |"^Though in F tonally Eb throughout. F.W.B." c/c/B/ A/B/G/ | F3 ||[M:6/4][K:Eb] C | 
 C G ^F G C D | E F E D2 D | C =B, C (E D) E | (F E) F G2 B | B G B !fermata!B !fermata!=A G/ | 
 F C D (E D) C | (F3 G/A/G/)F/ E2 F | G B G F3/2 C/ | C2 z2 ||[M:6/8][K:F] C/ | F/ F/ G/ A G/ | 
 F/ E/ F/ C C/ | F/ E/ F/ G/ A/ B/ | (c3/2 c) A/4B/4 | c/ B/ A/ G/ A/ B/ | c/ F/ E/ D B/4 B/4 | 
 A/ G/ F/ C/ D/ E/ | (F3/2 F) z/ |[M:3/4][K:G] C | C E G | G E G | G F D | C2 C | F E F | G c B | 
 (G3 | G2) C | [GE] [Gc] c | B A G | G C D | (E D) C | _B3 | c/>_B/ G C | E G _B/A/ | G3/2 F/ D | 
 (C3 | C2) ||  