After altogether too long, the seventh Doctor and Ace are presented as seen on TV. Prompted by Ace's memories of Perivale pensioners, she and the Doctor visit London during the early 1940s, the motive to let Ace experience the Blitz, which the Doctor hopes might cure her of her love of explosions. Unfortunately, there's a psychotic alien loose in the city.

It's easy to be cynical about the balance of effort in writing partnerships if one name is recognisable from another field. As a visual effects designer, Mike Tucker is not a name to give impetus to sales of a novel, so one assumes this is a genuine partnership. That the story was under consideration for season 27 of the tv show confirms this. Unfortunately, perhaps because of Mike's considerable experience of the show, Illegal Alien reuses too many ideas from previous stories. A duffel-coated Doctor in the England of World War 2 must invite comparison with The Curse of Fenric, and other elements of the plot and themes echo sections of season 25. In places, the writing is uninspired, illustrated by the lack of a better description of a time distortion than 'like wading through treacle'. The private eye and policeman in conflict is a particularly trite idea, presented here without any twist. Other characters, particularly the soldiers, are given clearer motivation and characteristics, and seem to fit into the 1940s setting more smoothly.

The first mention of Cybermen is dramatic, but blunted in effectiveness by the giveaway of the book's cover. And despite that cover and the text both suggesting Wheel in Space versions, I could not help but visualise the Cybermen as Invasion types - partly because of their lack of individuality, and partly because sections of the book are set in London sewers. The focus on the race rather than individuals works, as usual. The vivid description of them 'never surrendering, never retreating', while evocative, contrasts with their depiction in later tv stories and casts doubt on the likelihood of the story being considered for broadcast. There is certainly no role for David Banks.

In the first retrospective portrayal of these regulars in a novel, Ace is simplistically depicted as the kid of season 25. While we must ignore her subsequent development in the Virgin books, it's difficult to believe that this woman has experienced the catharsis of season 26. There is no urgent requirement for the late placement - the book could have sat between Dragonfire and Remembrance. Since there exists a series of post-Survival novels, trying to achieve something new with the younger characters might have been more worthwhile, and is certainly something I've been waiting to see.

The book is enjoyable, suffering mostly from a lack of originality. Perhaps not enough was altered from the submitted script, which would have needed rewrites before broadcast to remove too many similarities to shows then in production. However, although the writing is sometimes uninspiring, the story and characters are presented with clarity and gratifying economy.