One You have to admire the audacity of a Doctor Who writer whose novel quotes discursive interviews on the subject of Doctor Who - and approve of the sentiment expressed therein, that the strength of its format is flexibility. Such a strength is surely undermined, then, if development of the series is constrained by the desire to reconcile all contradictions, to maintain a rigid, cohesive continuity. For some, though, believability is inevitably compromised by freely igoring established history, even though the tv show itself developed that way.

And so The Infinity Doctors, despite its beautifully iconoclastic foundation, never conflicts with the ethos of the tv show, instead trying to provide something for everyone in a suitable anniversary celebration. It can be read as an informed take on how the 1996 tv movie might have turned out with a shift of emphasis in scripting, featuring a respectable, secretive Doctor who seems more inspired by Paul McGann himself than by that movie's eighth Doctor.

The setting is a recognisably conservative Gallifrey - albeit one with a darker, violent side - to which the Doctor has been indulged in his desire to meet warring alien races in an attempt at arbitration. While this unfolds, the integrity of time is threatened by a force operating beyond the limits of known space. The threat seems to gain in import with each page; this enhances the theme of an infinity of possibilities, but becomes overwhelming. Inertia of plot is the problem; the more massive it becomes, the slower it moves and the harder it becomes for the reader to focus on the details.

However, there's no need for harsh criticism - this novel is a careful development of what could have been a poor idea. For the 35th anniversary story we could have had another Eight Doctors, and this is a more imaginative and courageous move. One hopes it won't be the 40th anniversary before someone else gets the chance to do something like this; something totally dissimilar. The Infinity Doctors is original if obvious, laudable if not entirely satisfying - and therefore, a typical, atypical anniversary celebration.