The key to this puzzle is one the of the six suspects in the game Cluedo (Clue in the USA).
Their surname only is used. As in all Playfair Ciphers, any repetitions in the key are deleted.
EB HS SL GU CB EU UA HX LH FU IP AH
CX DC RW OQ VU XN CR IP ZX BW
OR RA BL MU IP BM ST RY EU SL XE SR