When Jodie Whittaker was revealed as the incoming Thirteenth Doctor over the summer Doctor Who fans were gobsmacked, with many surprised that the BBC had been brave enough to cast the first female incarnation of the Time Lord and manage keep the whole thing secret for so long.

However, there was one mega-fan who wasn’t quite so shocked about the announcement – former series boss Russell T Davies, who revived and ran the sci-fi series from 2005 to 2010 and had a bit of an inside track about the Tardis’ new owner (or at least her gender).

“Let’s just say I’m friends with all these people, with [current showrunner Steven Moffat] and with [new boss Chris Chibnall],” Davies told RadioTimes.com. “And we’ve been friends for years. So I knew what was in the air. I knew kind of.”

And so when Davies was contacted by BBC books to illustrate a new volume of Doctor Who poetry by novelist James Goss (called Now We Are Six Hundred and loosely based on verse by Winnie-the-Pooh author AA Milne), he couldn’t resist slipping in a few references to the series’ exciting future – even if he wasn’t sure of the specifics at the time.

“There’s a poem called Contents, which I thought ‘Well I’ll draw a trunk, and in that trunk there’s something representing every single Doctor,” Davies recalled.

“And that was tough, and that was me sitting there scratching my head for a long time on some of them. And I got there! And there’s also a handbag in there, you’ll be glad to see.”

And Davies didn’t stop there, also showing Peter Capaldi’s current Doctor looking significantly towards a female mannequin inside the Tardis (pictured, above) in one illustration, while another drawing appears to actually feature Whittaker’s Thirteenth Doctor in action – albeit in disguise.

“There’s a whole poem about an unnamed Doctor…. where is it?” Davies said, looking to his notes. “Oh yes, The Death List.

“Which has the kind of masked, unknown secret Doctor running around. On page 23, if you look at the swirl of those clothes she’s wearing women’s stilettos and the numbers 1 and 3 are hidden in the folds of those clothes.”

And if you can look closely the illustration in question below, you can see he’s right – so in a way, this is one of our first looks at a female Doctor in action.

“That’s a female Doctor running around!” Davies said.

“Well, I suppose anyone could wear high-heels, but there’s a curve there you wouldn’t get on a male figure.”

And even if his hunch about the female Doctor turned out to be wrong, Davies says he had a plan.

“I kind of knew anything could happen, so there was time with the publishing of it to have removed any of those,” he told us. “But actually they’re all quite speculative.

“Even if we hadn’t gone with Jodie Whittaker, that photograph of Peter Capaldi looking at the female mannequin represents that time when everyone’s saying there could be a female Doctor anyway.

“The illustration still stands, even if they’d gone and cast [Coronation Street star] William Roache as the Doctor. You could still have got away with that drawing.”

Speaking more generally about hiding such references in his drawings, Davies said: “Well when you’ve got a book of Doctor Who poems, you kind of know that’s really for fans.

“I mean I hope everyone reads it because it’s lovely and the poems are beautiful, and I think you could be six years old and have fun with it. Nonetheless, you are kind of looking at a niche market here. It’s not like photos of Daleks that are gonna appeal to lots and lots of kids. It’s very fannish.

“So I felt very free to get very fannish in it. There was a really mad Dalek toy made by Doctor Who adventures comic recently, which is the most misshapen Dalek ever. It got a kind of a cult following, it was such a bad Dalek toy. People kind of love it, fans, in a very niche sense, fans love it.

“So I’ve drawn that, that crops up about two or three times that mad little Dalek, the Doctor Who adventures Dalek.“So things like that are VERY specialist. But equally, then there’s Tom Baker with his scarf, and your mum and dad would know what that is.”

And soon enough, everyone and their mum will just as easily recognise the first female Doctor when she springs into action this Christmas – and her time hiding in the shadows will be a thing of the past.

Now We Are Six Hundred: A Collection of Time Lord Verse by James Goss and Russell T Davies is available for purchase in hardback from Thursday 14th September