I'd like to say that Westie is incredible, but that would be an understatement.
Focusing on the purser's margin for profit, it is interesting to reflect back to the Spithead Mutiny, where one of the major complaints was that the purser was taking two ounces out of every pound of meat...hence the term "the purser's pound", which was 14 ounces. For the sailors, it must have seemed incredibly unfair, but to the pursers, I suspect having that eliminated seriously impacted the profitability of their jobs.