David was almost cast in the Ninth Doctor episode " The Unquiet Dead" as the Victorian undertaker Gabriel Sneed, according to Gary Russell's book, Doctor Who:The Inside Story, the part was originally written for him.
David contributed the Forward for the book in which he informs us that "It is the law of television that script read throughs must always be accompanied by coffee and pastries." When talking about getting back to work he also states that, "working on this show grips you with a fevered and slightly worrying, all consuming obsession and it's much easier to spend time in the company of fellow sufferers."
The Forward also contain one of my personal favourite turns of phrase from David, (Phil Collinson) "beaming at his assembled team, who all grin back, Who-madness glinting off their teeth."
IMHO - It just doesn't get better than that!