This title was illustrated in black & white and published in picture-book form by the Bodley Head in 1982.  Then it was published in one volume by Puffin with Captain Pugwash and the Mutiny in 1985 and reprinted in 1987 and 1988.

Captain Pugwash’s devious plan to refill his empty treasure-chest goes awry when some uninvited ‘guests’, in heavy disguise, interrupt his fancy dress party. Only Tom, the clever cabin boy, knows who they are!