The Pirates! In an Adventure with Communists

I've been thinking of an adventure more along the lines of pearl-smuggling in the South Seas or discovering a lost continent. We're being sponsored, you see, so it's got to be full of glamorous locations and scantily clad women.
He's conquered the seven seas, hunted Moby Dick and rescued Charles Darwin; now the Pirate Captain and his crew are off on another adventure. Their mission this time: to sail to London, buy a new suit for the Pirate Captain and maybe have some sort of adventure in a barnyard.
But nothing is ever straightforward for the hapless pirates. In no time at all, the Pirate Captain is incarcerated at Scotland Yard in a case of mistaken identity. Discovering that his doppelganger is none other than Karl Marx, the Captain and his crew are unwittingly caught up in a sinister plot involving communists, enormous beards and a quest to discover whether ham might really be the opium of the people.