The year is 16127. Four decades have passed since the colonists of Nerva Beacon returned to repopulate the once-devastated planet Earth - and the chosen few are finding the business of survival tough. Far beyond the sterile safety of sanitised Nerva City, transmat scientist Roger Buchman has brought his family to an island surrounded by what they once called Loch Lomond, hoping to re-establish the colony he was forced to abandon many years before. But something else resides in the loch - a pestilent alien infestation that the Doctor, beaming in from Nerva City, remembers only too well from his time aboard the Beacon. The Wirrn are back - and they’re hungry...

Wirrn Isle is a curiously hybrid beast, rather like the Wirrn-human fusion we encounter in this story.

Though intended to exploit the popularity of The Ark in Space, in particular the insect foes faced by the Fourth Doctor in that serial (as explained during the 15 minutes of interviews at the end of Disc Two), the first half of Wirrn Isle could have featured any creature really. Here human intelligence is combined with a giant insect body not via the Wirrn’s usual method of absorbing the knowledge of their ingested prey, but as the result of a transmat accident. Thus William Gallagher’s script plays out more like a Doctor Who spin on The Fly than a follow-up to The Ark in Space.

Many of his character names don’t reflect the earlier serial either. Whereas in 1975 we had exotic, futuristic names such as Vira, Rogin, Lycett and Libri, here we meet a husband-and-wife team, Roger and Veronica Buchman (Tim Bentinck and Jenny Funnell), whose names appear to be deliberately mundane versions of Rogin and Vira. They have given their children the rather bizarre monikers of Iron and Toasty (Rikki Lawton and the endearingly voiced Tessa Nicholson - who should definitely do more stuff for Big Finish). Of the Nerva descendants, only Paul (Glynn Sweet) seems like an authentic name to me, being a Biblically inspired designation for a leader, like Noah in Ark. Nor do these humans use the peculiar and precise speech patterns of Vira’s crew, though this could be a result of cultural blending with GalSec colonists - of whom we meet a couple of examples in the final two episodes.

Don’t get me wrong: the first half of Wirrn Isle is exciting and gripping enough, especially the tense scenes in which poor Flip (Lisa Greenwood) is trapped on Loch Lomond, affixed to the ice by her own frozen blood. It just doesn’t feel much like a sequel to The Ark in Space.

That situation improves during the second half of the story, in which the scope of the threat is opened out and we meet GalSec descendants Sheer and Dare (Dan Starkey and Helen Goldwyn), who sport Sontaran Experiment-inspired South African accents.

Sound designer Simon Robinson creates a different sound for the transmat beam than the effect used in The Ark in Space and The Sontaran Experiment, though his incidental score is more authentic, evoking the era of the Sixth Doctor (Colin Baker) by being more conspicuously electronic than a lot of other composers’ recent music for Big Finish. Just less than 15 minutes of this music can be heard at the end of Disc One.

My marks out of ten may have diminished slightly as this Sixth Doctor and Flip trilogy has unfolded, but it’s been great having this new dynamic to the TARDIS crew. I look forward to hearing from them again.

7

Richard McGinlay