1. THERE'S A TRAGIC ROMANCE
All right, so maybe "tragic" is over-egging it just a tad. The right word is probably "silly". But in one of the Christmas specials, we do get to see Tracey have an ever-so-passionate romance with a mechanic called Manfred. Who lives in Germany. While she's on a strange, secret mission to do with a valuable antique car and the history of the Cold War. Who knew Birds of a Feather could go so John le Carré on us? Don't worry, though - there won't be any interrogations in anonymous hotel rooms with sinister spies (though that would probably be right up Dorien's street).
2. THERE'S AN AMAZING PRISON BREAK
Darryl and Chris aren't exactly the criminal masterminds of the century. We all know this. But dim and misguided as they are, they actually manage to pull off a daring prison break in one of the Christmas specials. We won't give away the details, but let's just say it doesn't involve digging a tunnel with plastic prison spoons (as if Chris would ever bother making so much effort). So will the sisters be overjoyed to be reunited with their fugitive fellas, or will it just spoil their holiday in Majorca?
3. THEY BECOME CAMPAIGNERS FOR JUSTICE
One thing we'll say about Sharon and Tracey: they're not under many illusions about the men in their lives. Chris and Darryl are no saints, and the girls are fine with that (well, not exactly fine, more like chronically exasperated, but you get our point). And yet, there's a Christmas special where the sisters realise the convictions might be unsafe, and a bent copper might have stitched them up. Before you can say "Are you sure this is a good idea?" the girls start a media campaign for the release for their beloveds - who are promptly re-named the Chigwell Two. Could this really have been the greatest miscarriage of justice in British legal history? Somehow, we doubt it...
4. YOU CAN DO SOME STAR-SPOTTING
Chigwell might not be renowned for its celebrities (unless you count the occasional young male model Dorien sets her sights on), but one very special Christmas episode sees the girls jetting off to Hollywood to mingle with the great and the good. It's all because Sharon and Tracey get the idea that their real biological father is none other than mahogany-skinned matinee idol George Hamilton, and the man himself actually turns up in the episode. Along with George Wendt (aka Norm from Cheers) and a certain very famous British celebrity who we can't possibly name. (Oh OK, it's Richard Branson.)
5. YOU'LL ENTER A PARALLEL UNIVERSE
Ever wondered what life would be like if, say, Chris was a famous rock star instead of a bitter jailbird, and Sharon was his pampered diva wife? Well, that's the strange parallel reality we see in one Christmas episode. Don't worry, the show hasn't gone all sci-fi on us: it's just an extended fantasy of Sharon's after she has a bit too much Crimbo booze. But it certainly makes for entertaining viewing - especially when Dorien appears as the prim, god-fearing cleaning lady.
6. DORIEN'S MUM TURNS UP
As if all the reasons above aren't enough to make us catch the Christmas specials, here's another. One of the episodes features the only on-screen appearance of Dorien's mother. It's true. And there we were thinking Dorien never had earthly parents, and was simply a magical being composed entirely of lust and luxury couture...