Oh I agree completely, I support multiple canons all the way. Schrödinger's Canon, I like that! :D With a show as (damn near inherently) full of contradictions as Doctor Who, whittling it down to One True Canon seems like throwing out the baby with the bathwater.

A mistake? Heh! I never heard that - As I recall there's continuity in the following books about losing all their stuff, and the AU Old Girl being extra-tetchy because she didn't like them. It's possible they edited that in at the last minute.