Its on next Saturday as well. BBC4 you are spoiling us!
This was filmed at Gartnavel Royal wasn't it? If so that was a missed opportunity as I used to live in the nursing accommodation there, the patients from the mental hospital would sometimes wander down in their pjs - and sometimes without. No sign of his Tennant-ness though - just think, all those young, free and single nurses as well, he could have put in practice for his Doctor Who activities.