In amidst all the death, Cybermen attacks and almost-regenerations (for both the Doctor and the Master) in the Doctor Who series 10 finale, you’d be forgiven for missing one of the subtler Easter Eggs inserted by outgoing series showrunner Steven Moffat.
However, luckily for you (and us) the Who boss recently revealed one more secret about The Doctor Falls – and it turns out it’s related to his predecessor in the top job Russell T Davies, who revived and ran the BBC sci-fi series from 2005 to 2010.
“When people want to exaggerate a number, they always have a favourite number,” Moffat told The Doctor Who Fan Show. “Russell always uses 57, always 57.
“I once eventually said to him, ‘Do you have a preference for Heinz products?’ – he didn’t even know what I was asking him – ‘Because it’s always 57! Even in scripts, if you’re exaggerating, you always say 57. That’s your go-to.’”
Accordingly, then, when Moffat had to choose a floor number for the colony ship solar farm that would host the Twelfth Doctor’s last stand, he knew exactly what to go for – the sort of number that RTD himself would approve of.
“It’s Floor 507 in tribute to Russell,” he concluded.
Of course, it’s also possible that the number has ANOTHER secret meaning, given the regeneration-heavy content of the episode – 507 was previously cited by Matt Smith’s Eleventh Doctor (almost certainly in jest) as the potential number of regenerations for a Time Lord during a guest appearance in spin-off series The Sarah Jane Adventures.
Accordingly, when this number appeared in some promotional materials for the latest series fans suspected a regeneration tease, which they eventually received. But was floor 507 also a callback to this moment or just a coincidence, given that it was 57-loving Davies who wrote the original Matt Smith gag?
We may never know – or at least until the next post-episode discussion hits YouTube.