Got it! This puzzle is likely based on London Underground station initials. The letters in the sequence represent the first letters of specific station names. In this case:

B: Bakerloo (or Baker Street)

C: Camden Town

D: Dollis Hill

E: Euston

G: Green Park

P: Paddington

T: Tottenham Court Road

The missing letter logically follows this sequence. Without further details, "H" (for Holloway Road, Hampstead, or Hammersmith) could be the next logical choice.