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How many impossible things can you believe before breakfast? I'll Explain Later's 27th episode whisks you away to unimagined realms and mythical times. Tegan might not be well drawn, but her draughtswoman credentials are not in doubt. A smörgåsbord of cultures let bygones be Bigon as the Fifth Doctor takes Four to Doomsday.

Incoming showrunner Chris "safe-hands" Chibnall once again nails a chilling dystopia with his uncanny depiction of a future economy in which a world-leading project can employ just four workers - and inept ones at that. No portentous voiceover can sate The Hungry Earth, nor warm Cold Blood.

And meta machinations manifest massively, as First Doctor William Hartnell lands the Tardis on the sets of Ben Hur and Quo Vadis. With content so fantastic, surely it's churlish to question what The Romans have done for us?

Along the way, John sets Jim straight, Jim goes pop and Matt polices firework safety.