Downton thrives because it achieves a near-perfect blend of fact and fiction - with real events setting a context for the ups, downs and sideways for the Earls of Grantham. The very first episode of the very first series set the tone, with news solemnly reported of the sinking of the Titanic.
While Downton has been a phenomenon, a smash hit on both sides of the Atlantic, it bears many similarities with medieval and ancient Greek literature: blockbuster epics where the blend of reality and a bit of artistic license made story-lines as explosive, dramatic and gripping as the Sunday night prime-time slot is today.
The Alexiad was written in the 12th Century, for example, after the Empress Eirene asked for a good, racy account of the below and above stairs plots in the palace that would have given Downton a run for its money. Ooh - the servants Borilos and Germanos were planning a take-over from behind the scenes in 1080; who'd have believed it ! She even turned to a new writer to keep it going after the first person she commissioned keeled over and died after working too hard (that, and falling ill while on military campaign).
But ancient and medieval literature was no different. There were endless slinging matches between authors with rival accounts of what had 'really' happened. This naturally makes unpicking the narrative accounts and telling reality from make-believe really quite hard.
The point of the literature was to amuse and instruct, to give an insight into the past; it was certainly not to give a fact based account of history, reported in tones reminiscent of 19th century newspapers that would send you to sleep and question whether improving national literary levels were really worth the trouble. On the contrary - the more skullduggery, evil villains and heroic acts of selflessness the better.
Or Homer, with the twisting plot lines, carefully-weaved story that was too neat and predictable for some. Well, of COURSE, Odysseus was going to make it home; what did you expect ??! Would his beloved old dog recognise him after only 20 years away; this is showbusiness, guys, so you do the maths. That Cyclops - did you really think he'd snaffle the hero ? Was that nice Branson going to - oh wait, that's Downton again.
The point is that Entertainment is, well, Entertainment. After my bit to push X-Factor viewing figures clearly worked last week, I'm hoping to have the same effect on Downton Abbey. Julian Fellowes, Anna Komnene and Homer; Lady Mary, Alexios Komnenos and Odysseus. 3,000 years of prime time all linked neatly together. You read it here first, people.