This episode sees the first appearance of Clare Keightley, played by Susannah Harker. It was obvious from the first read-through that there was a wonderful chemistry in the Chris/Clare double-act, not to mention in the Doctor/Clare relationship.

Actually, the Doctor's first meeting with Clare, which happens towards the end of this episode, has become one of my favourite scenes in the whole piece: sparky, light and just the right side of flirtatious. In fact, Susannah got on so well with Paul that, as a direct result of their working together on Shada, the pair of them recently appeared together in a two-handed play called The Little Black Book at London's Riverside Studios. And an excellent show it was too.

This episode culminates with the famous bicycle chase. In the television version this sequence provided a picturesque showcase for the Cambridge locations, as the Doctor was pursued by the Sphere through the streets and colleges, encountering pedestrians, choristers and Skagra himself along the way.

Ours is a rather shorter and more audio-friendly variation, but I think you'll enjoy it all the same. Paul had a whale of a time simulating the sound of his voice juddering as his bicycle rattled down a set of stone steps!