The Ds are the people in Round about a Pound a Week: they live in cramped cottages, scraping together a living. The As occasionally take them some gruel. But do nothing else. A lot of them are put in prison (actual or metaphorical) by the As, hence the line of prisoners shuffling along, going off to ‘forced labour’. Honestly, most readers of the Post will be feeling angry already and they haven’t even read the book yet. But actually it’s funny and extremely readable, oddly enough rather like a politicised Lady Rose and Mrs Memmary in tone – the fury is subdued by humour and a kind of rueful acceptance of man’s beastliness to man.