What the hell was that the Doctor was eating?

What was the thing on a stick that made Bill pull that face but which the Doctor called "my favourite"? Roast ox was one of the most popular delicacies at the Frost Fair, so we were guessing – apologies in advance – that it was a bull's penis. Our sources assure us we're wrong but are only willing to narrow it down to "some kind of offal". Yum.

What were the Doctor and Bill drinking?

The Doctor's suggestion that Londoners would forget the strange events of the Frost Fair due to copious day drinking makes a lot of sense. Alcohol was everywhere, with people partaking of gin, a strong spice-infused beer called Mum and Purl, a blend of gin and wormwood wine (think absinthe/vermouth) which was served hot. We don't know which of the above the Doctor and Bill have in those rather dainty looking cups but we like to think they dived straight in to the Purl.

Did an elephant really walk on the Thames at a Frost Fair?

Yes, that actually happened, back in 1814. Read more about the Frost Fairs here.

Didn't the Doctor and River Song once visit a Frost Fair? 

They did indeed, as briefly referenced by the Doctor in this episode. And in going back, the Doctor may have been taking a risk of bumping into himself... Get the full details here.

What was that story the Doctor was reading to the children?

Yes, that was a genuine bedtime story the Doctor was reading to the orphan children, but before you start saying 'Aaaah', it's not the kind that's likely to have given them sweet dreams. Find out all the gory details here.

Has anyone else almost used a swear word in Doctor Who?

There was a cheeky moment when Bill learned that the mysterious fishy fuel being dredged out of the Thames could burn under water, responding "No sh-" before we cut to the next scene. Certainly not something that is going to offend anyone in this day and age, but given that Doctor Who is a show aimed at children as well as adults, has it featured any other such moments in its 54-year history?

There are suggestions there may have been similarly close calls with a slightly stronger four-letter word, courtesy of Adric in classic Who story Kinda, Lady Cassandra in Tenth Doctor adventure New Earth and Deep-Ando in series nine episode Sleep No More, who were all cut off before they could add the final syllable. And after series six episode Let's Kill Hitler aired, some viewers were convinced they'd heard a fully-fledged F-word – despite the BBC's assurance that it had actually been part of a German phrase “Halt, was machen sie?” meaning, “Stop, what are you doing?”

Down the years, there have also been assorted damns and goddamns, a bitch from Missy and an arse from Clara, all pretty harmless. But far more shocking is the use of the N-word in the rhyme Eeny, meeny, miny, moe in 1966 episode The Celestial Toymaker, which would quite rightly be unthinkable today. That's one respect in which times have certainly changed for the better.

Was that Nathan Barley playing the baddie?

Yes, that was indeed Hoxton's finest – AKA actor Nicholas Burns – playing the nasty Lord Sutcliffe. Read about what else he's been up to here.

Who was that banging on the vault doors?

At the end of the episode a worried Nardole heard banging from inside the huge metal vault the Doctor has been sworn to guard – and at the same time we heard another sound that might just be a clue as to who or what is inside. Read our theory here.

Doctor Who continues on BBC1 at 7:20pm on Saturday 6th May