One of the many unofficial spin off movies from the BBC TV show "Doctor who", created using a contract loophole which allowed production companies to license characters directly from their creators.
Jemma Redgrave assumed the role of Kate Lethbridge-Stewart in Series 7 of Doctor Who (2005).
The second time John Leeson isn't playing K9 but a different character, the first was in "the power of Kroll" when the original cast actor for Duggen Martin Jarvis was forced to drop out at the last second, and with Leeson on contract for the season and K9 not able to appear due to the location he was brought in as a replacement.