The Doctor (Jon Pertwee) and Sarah Jane Smith (Elisabeth Sladen) return to London in the mid-1970s to find it deserted except for looters, borderline fascist troops imposing martial law and herds of rogue, hilariously unrealistic prehistoric creatures roaming the streets.

After being attacked by a pathetic puppet pterodactyl, trying to lasso a matte painting of a triceratops and getting frowned at by a rubbery tyrannosaurus, the Doctor establishes that it’s all part of Operation Golden Age: an attempt by some hippies, loony scientists and treacherous soldiers (including, in a clever but immediately obvious twist, UNIT semi-regular and PTSD-sufferer Mike Yates) to return polluted, overrun planet Earth to a cleaner, freer, utopian state.

With his usual combination of gurning, grumbling and condescension, Pertwee does a lot of running around, getting arrested, escaping, running around again, being arrested again, being incorrectly framed, being horribly wrong, being rude to Sarah (‘No relation,’ he specifies after giving his name as Doctor John Smith during a military interrogation) and eventually saving the day, although he can’t overcome the greatest enemy of them all: the dodecahedral-ply padding of the preachy script and the not-at-all-special effects.

Only the eternally impressive Lis Sladen emerges with much credit from a fatally overambitious and overblown attempt at something that stops being funny-rubbish after about three episodes and becomes unbearably rubbish instead. A sanctimonious diplodocus of a serial.

Extras: Of course, even the most dismal Doctor Who stories are usually rendered bearable – and, of course, the BBC hopes, buyable – by the dense bolus of bonus material on the DVDs.

Invasion of the Dinosaurs isn’t overburdened with extra excitement, but it contains enough items of interest to make it worthwhile forking out for the UNIT Files boxset. Just.

The commentary is solidly unspectacular. With Pertwee, Sladen and Nicholas Courtney (the Brigadier) all sadly no longer with us, it’s left to director Paddy Russell, actors Richard Franklin, Terence Wilton, Peter Miles, production designer Richard Morris and script editor Terrance Dicks (‘Barry Letts got in touch with some company or other and said, “Can you do a convincing dinosaur for us on our budget?” and they said, “Yes we can” – and they lied’) do their best to talk through a very tedious story. Even moderator Toby Hadoke sounds as if he’s struggling to make it through to the end.

People, Power and Puppetry, the principal documentary, features Matthew Sweet talking enthusiastically and at length about how the story reflects the ‘bitter cultural debate’ of the 1970s: population management and the threat of democracy being dismantled in favour of a more dictatorial model.

There’s also a lot of apologising for the atrocious monsters. ‘It was a good script,’ producer Barry Letts remarks, ‘but the dinosaurs looked awful.’

Doctor Who Stories features the first instalment of reminisces by the late Elisabeth Sladen about her time on the programme, including tales of CSO underwear, driving through rush-hour traffic in the Whomobile (‘The police came up and said, “Doctor, do you think you could not drive it… could it be taken on a prop van?”’) and the two principal actors with whom she worked during the seventies (‘As far as Tom and Jon were concerned, I think there’s a moment where they think, “I am the Doctor”’).

Every story that Lis tells is imbued with a spirited mischief and a genuine love for the show, and while it’s a hugely enjoyable featurette – albeit with footage cribbed from a 2003 documentary – it’s tainted with sadness at the knowledge she’s no longer around.

Elsewhere, there’s a chance to watch Episode 1 – of which only a monochrome copy was left in the BBC archives – in colour rather than black-and-white; Jon Pertwee turns up at Billy Smart’s Circus in an awkward skit with two kids; the regular Now and Then feature revisits the London locations of the story, including Lambeth Pier, which featured in 2006’s Rise of the Cybermen; John Levene does a snippet of commentary (‘I said, could Jon not look at me when he says, “large, dumb and very stupid”?) and there’s the usual trailers, PDFs, photo gallery and a couple of highly inessential deleted scenes.

Released on DVD on Monday 9th January 2012 by 2entertain.

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