Should be. Musical instruments are allowed on-board even ex-LHR. It was not during the one-hand luggage rule days. Lots of room in CW.
Suggest you mention it at check-in.
Saw a pax with a guitar boarding First a couple of months ago. He was strumming his guitar in the Concorde Room for ages - there should be a rule against this! He wasnt even good. Wonder if he was composing ?