Fans of Sylvester McCoy will be delighted with the release of The Silurian Candidate today.

The year is 2085, and planet Earth remains on the edge of a nuclear precipice. At any moment, either of two vast rival power blocs, to the west and the east, might unleash a torrent of missiles, bringing about the terrible certainty of Mutual Assured Destruction.

But there is another way – or so Professor Ruth Drexler believes. Hence her secret mission deep in Eastern Bloc territory, to uncover a hidden city, never before glimpsed by human eyes: the Parliament of the Silurians, the lizard people who ruled Earth before humankind.

There, she’ll encounter a time-travelling Doctor, who knows the Silurians well. A Doctor on a secret mission of his own.

Writer Matthew J Elliott tells us more, “Not only was it a tremendous honour to add another chapter to the story of a classic Who monster, but pairing them up with the devious Seventh Doctor gives the plot an angle no other Silurian story has ever had.”

Also out today is Time in Office, the next tale in the Doctor Who Main Range where the Fifth Doctor, Peter Davison, will finally (be forced to) ascend to the High Office of President of Gallifrey. ALL HAIL PRESIDENT DOCTOR!

The Doctor's adventures in time and space are over. The Time Lords have recalled him to Gallifrey – but what he faces on his home planet is worse than any trial. Following the disappearance of President Borusa, the High Council condemned him to the highest office – and he can't evade his responsibilities a nanosecond longer...

So all hail the Lord High President! All hail President Doctor!

Rassilon save him. This time, there's really no escape. 

"A lot of people have asked me where I got the idea for this one, and the answer is "from Alan Barnes", writer Eddie Robson tell us, "- he just asked me if I'd like to do a story about the Doctor being forced to take the Presidency, post-Five Doctors, and it sounded great so I said yes! I immediately felt this would work best as a quite comedic one - my favourite version of Gallifrey is the one from The Deadly Assassin, the decadent, change-resistant version, full of pompous oafs, and my favourite TV shows about politics are things like The Thick Of It and the original House Of Cards, which has lots of humour in it. So I instinctively went in that direction.

"And yes, I believe it is the first time Tegan and Leela have met! They're very different personalities, but they're both direct in their own way - Leela doesn't know how to choose her words carefully and Tegan doesn't care. Tegan does feel a bit isolated at times, because the Doctor's pleased to see Leela again and she knows the situation on Gallifrey, so Leela becomes his right-hand woman. And Tegan is left kicking her heels and finding out just why the Doctor left Gallifrey in the first place..."

Make sure you pick up these two adventures, both available at £14.99 on CD or £12.99 on download. All CD purchases unlock a download exclusive which works with the Big Finish app.

Or you can save money by getting a subscription to the Doctor Who Main Range. When you subscribe you'll get 30% off the price, free specially recorded Short Trips stories, PDFs of the scripts and extended downloadable extras. You can subscribe for either 6 or 12 releases.

And if you’re new to the Doctor Who Main Range stories, you can try an extract of The Silurian Candidate when subscribing to the Big Finish newsletter.

Coming next month, the Sixth Doctor is reunited with companions Flip Jackson and Constance Clarke in The Behemoth.

Bath, 1756 – and a very dashing gentleman known only as the Doctor is newly arrived in town, accompanied by his lady friends Mrs Clarke and Mrs Ramon. He’s created a stir among the gentlefolk of Georgian high society – and a stir in the heart of merry widow Mrs Theodosia Middlemint, rumour has it.

They are not the only strangers from abroad causing tongues to wag, however. The mysterious Lady Clara, come from Amsterdam in the company of the noble Captain Van Der Meer, has the whole of Bath agog. Who is she, really? What is she, really?

But there’s something terrible beneath the veneer of Georgian gentility. As awful a horror as the Doctor has ever exposed, hidden inside Balsam’s Brassworks. Something that needs to be brought to light, for the sake of all humanity.