Accountancy has a reputation for dullness but its history is the history of civilisation itself, from the evolution of government and taxation to trade and capitalism. It has also provided a paper trail through some of the darker periods of human history.

At first sight it looks like the income statement for any factory. It starts with the daily wage bill, and deals with the costs of uniform and other running expenses, all properly amortised.

But then comes an odd line: the projected income per worker is adjusted so that it covers not one year, but only nine months.

For this is no ordinary factory, but Buchenwald concentration camp. The workers, leased out by the SS, are expected to be dead from exhaustion in less than a year.

Further down in the accounts is a note: "revenue at death". This refers to the sum to be made from the body itself, from ashes, fat and hair.