Shades of Yellow

I have been browsing in le Carré's Letters, published last year. He remarks to an agent and publisher about the lamentable paper now often used for hardbacks, which yellows swiftly. He calls them "paperbacks in disguise". Well put. Such was his complaint that a better paper was used for an imminent novel - but the irony is that this volume of letters, which costs £30, is printed on rough paper.