As a huge fan of the first ever episode The killings at Badger's Drift, it came as no surprise to me that they decided to reference that great story. Dead Letters is a great episode, which sees two great characters seemingly brought back from the dead, The Rainbirds.
The story is very good, full of intrigue, but it's the characters that make this one so watchable. Elizabeth Spriggs and Simon Callow are two of my favourite performers, and both are simply brilliant, Spriggs essentially re-creates Iris Rainbird, she's obnoxious and nasty, whereas Callow is excellent as the chain smoking and womanising Doctor.
You can't help but watch this without smiling, there are some wonderfully humorous moments, but for fans of the show like me, you'll love the references, even the name 'Bella' takes you right back to the beginning.
Had the killer had a little more screen time prior to the conclusion I'd have given this a perfect 10, the ending seemed a little contrived, but all in all this is a gem of an episode 9/10