IMDB has updated the cast list - not as complete as Paul Kidby's list but with a few new additions - namely:

Mr Brown - Geoffrey Hutchings
Unseen University student wizard - David Decio

and last but not least - The Toymaker - TERRY PRATCHETT (Yay!)

Also Kevin Wickenden is listed but still does not have a role as such.

More updates as they come through.
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RA