Amicus’ first foray into the science fiction adventure, The Land That Time Forgot (UK, Kevin Connor, 1974) did rather well at the box office – well enough for the studio to set wheels in motion for a follow-up. At The Earth’s Core (UK, Kevin Connor, 1976) aimed to build on that success but made some not-insignificant changes to the formula.

The Land That Time Forgot was the 14th highest-grossing film released in 1975, which may not sound too impressive on the face of it, but there were 66 films produced in the UK in 1974. Moreover, it was up against US blockbusters such as The Towering Inferno (US, John Guillerman, 1974) and features like the latest James Bond, The Man With The Golden Gun (UK, Guy Hamilton, 1974). There was even a conceptually similar Edwardian-set fantasy adventure The Island At The Top Of The World (US, Robert Stevenson, 1974) from Disney to contend with. On that basis, The Land That Time Forgot’s audience was very healthy, and considering the modest budget the resulting profit was very welcome. (The Island At The Top Of The World was made for $8 million, considered low-budget by Disney despite being more than ten times the budget of the Amicus picture). At the Earth’s Core would reportedly have double the budget of its predecessor, at $1.5 million – still peanuts compared with the big studios.

Naturally, the follow-up would be another Edgar Rice Burroughs adaptation. It would not, however, be another story from the same series. The Land That Time Forgot was a novella published by Burroughs in 1918 about the mythical land of Caspak, which was quickly followed by two sequels – although they were not direct sequels to the first story, each following different main characters and taking place partly concurrently.

Instead, director Kevin Connor and producer John Dark chose to adapt At The Earth’s Core, the first story in another Burroughs series, the Pellucidar sequence, set in a fantastical land in the interior of the Earth.

Not unlike the preceding film, At The Earth’s Core, sees adventurers from recent history (the late Victorian period in this case) aboard a newfangled vehicle (a drilling machine in place of a submarine) who become lost and find themselves in a bizarre and dangerous world populated with primitive humans and prehistoric beasts. In a twist from the typical ‘lost world’ setting, all of ‘Pellucid’ (shot entirely in-studio) was enslaved by the Mahars, a form of evolved, telepathic pterosaurs whose psychic hold would have to be broken if Innes and Perry were to escape.

Unsurprisingly, Kevin Connor had been given the job of directing, having done a good job on The Land That Time Forgot despite no previous experience in the genre. Also returning for a second appearance would be lead actor Doug McClure, who the US financiers had insisted upon. In retrospect, McClure seems an odd choice, lacking sufficient clout to guarantee a US audience but still costing significantly more than many an established British star. But although McClure had been a handful on The Land That Time Forgot, reportedly drinking to excess, he had impressed Connor during action sequences, which most British actors, their backgrounds in theatre or kitchen sink TV dramas, lacked experience of. “In fight scenes he was especially good due to his hours of American TV action films,” Connor recalled. “He knew exactly where the camera was at all times and threw punches precisely where the effect would work for the screen.”

There would be more fist fights and physical action on At The Earth’s Core for McClure to get his teeth into. While its predecessor had been surprisingly cerebral in places and played absolutely seriously, the new film would revert to a campier, pulpier tone more reflective of the source material. Joining McClure would be Peter Cushing, who Connor had directed in horror portmanteau From Beyond The Grave (UK, Kevin Connor, 1974).

Arguably the standout features of The Land That Time Forgot had been the special effects and creatures, by effects maestros Derek Meddings and Roger Dicken respectively. Dicken had been unimpressed with how his creatures had been filmed in the earlier film and disappointed with the lack of control over his creations. As a result, he declined to do At The Earth’s Core and therefore a significantly different approach was taken, replacing Dicken’s ‘activated puppets’ with men in suits.

“We tried to get the beasts bigger so as to interact better with the actors – more one on one,” Connor said in an interview with HeyYouGuys,com. “We had a somewhat bigger budget thanks to the success of ‘Land.’ The beasts were specially designed so that small stunt guys could work inside the suits in a crouched position and on all-fours.” The results include a terrifying pursuit by an outsized Psittacosaurus (which was in reality around two metres long but here is as big as a Tyrannosaur), a fight between two tusked Brontotheriums and McClure going toe-to-toe with something resembling a firebreathing, waddling Ankylosaur.

It’s certainly no worse than the effects in Toho’s contemporary Godzilla films but it can be extremely difficult to shoot a man in a suit in such a way that it does not look like a man in a suit. (To be fair, the quadrupedal monsters work better than the bipedal ones in this regard). Ultimately, Roger Dicken puppets would have elevated the monster sequences considerably, though the inherent silliness of the film compared with the previous one means the odd obvious rubber costume matters rather less than it might.

There was a lot less miniature work this time, chiefly restricted to the beginning and end of the film with the ‘Iron Mole’ drilling contraption which takes Innes and Perry to ‘the Earth’s Core’. Meddings’ old role was taken by another alumnus of the Gerry Anderson Century 21 academy, Ian Wingrove, and it’s probably no surprise that the impressive vehicle resembles a steampunk version of the Thunderbirds’ ‘Mole’.

Principal photography began on 26 January 1976, at Pinewood this time (The Land That Time Forgot had been filmed at Shepperton) and lasted for nine weeks. By this time, Milton Subotsky, the heart and brains behind Amicus, was on his way out, and it would be the last film the studio produced on his watch. In fact, he had little input into At The Earth’s Core and claimed in a 1985 interview that by this time he had been locked out of involvement in production due to his failing relationship with partner Max Rosenberg.

As David Innes, McClure was just as solid and likeable, if unremarkable, as he had been in The Land That Time Forgot – indeed, the character is virtually the same as that of Bowen Tyler, and most of Burroughs’s main characters. Abner Perry was not, it seems fair to say, a vintage Cushing role. The somewhat stereotypical bumbling British professor, frequently oblivious to the horrors and wonders around him, was a largely comic creation invested with little of the subtle complexity that Cushing often imparted. BFI Screen Online noted, “It is hard to tell whether he is enjoying the role or just doesn’t know what to do with it.” It’s an enjoyable performance for all that and its shallowness is not out of keeping with the narrative, an intellectually simpler affair than its predecessor.

The Land That Time Forgot had eschewed the ‘hot cavegirl’ cliché, and its lead female character Lisa Clayton, while required to scream and be rescued on occasion, was also both capable and generally clothed sensibly. The chief female character of At The Earth’s Core, Dia (Caroline Munro), is, by contrast largely reduced to the status of eye candy and a trophy for Innes to fight over with other potential suitors Jubal the Ugly One and Hoojah the Sly One. (Burroughs did not believe in beating around the bush when it came to characterisation).

One of the really notable features of the film is its sound design, developed under Jim Atkinson, which absolutely captures the unearthly nature of Pellucid. The sound, together with the production design (by Maurice Carter, who had the same brief on The Land That Time Forgot) assisted by Mike Vickers’ music, never allows the viewer to forget they are visiting an alien world. The reverberating bellow of the Brontotherium, the unrelenting shriek of the Psittacosaurus and most of all, the backwards, echoing chatter of the Sagoths, produce a particularly unsettling and otherworldly effect.

The soundtrack itself is an unusual feature of the film, combining electronic elements with more conventional instrumentation. Mike Vickers, an early member of Manfred Mann before striking out as a solo artist, conductor and composer, was an early adopter of the Moog synthesiser. This certainly comes through in the distinctive sound of At The Earth’s Core.

My first experience with this film was at the age of around four or five, watching it on television at my grandparents’ house. I remember the opening titles quite clearly, with the industrial sequence of flowing molten metal and then swiftly into the ‘Iron Mole’ to drive into the hills. The descent into the earth as the Iron Mole resists its pilots’ control is genuinely tense, and just as all seems lost, it bursts into a weird jungle landscape. I didn’t make it very much further – the appearance of the Psittacosaurus, its hideous shrieks and close-ups of its snapping beak, were too much and I was so distressed that the channel was changed. (The film’s tagline ‘Take The Most Terrifying Journey Of Your Life’ might seem ridiculous now but it was true for me then).

I finally saw the whole film a bit over four decades later in preparation for this article. I’m not sure what I was expecting but having watched all three of the Amicus Burroughs adaptations together plus their near relation, EMI’s Warlords of Atlantis (UK, Kevin Connor, 1978), At The Earth’s Core really stands out visually, aurally and in tone. It’s the least serious of the series, right up to the final tongue-in-cheek frames, but tries hard to differentiate itself from other ‘lost world’ films with a unique look and sound. It has dated less well in some respects than its partner pictures but the sound design and music now seem rather innovative. The Iron Mole is a truly classic bit of steampunk design, up there with the Nautilus from 20,000 Leagues Under The Sea (US, Richard Fleischer, 1954).

As with The Land That Time Forgot, At The Earth’s Core did well enough to spawn a follow-up, which would emerge as The People That Time Forgot (UK, Kevin Connor, 1977). By then, however, Amicus was on borrowed time.