The Lewis Carroll poem The Hunting of the Snark (An Agony in 8 Fits), follows the misadventures of a group of seafarers, amongst them a banker and a broker, as they search for the elusive mythical beast. We are warned at the outset that catching Snarks is all well and good, but beware if your Snark is a Boojum, because - well, we’ll come to that.