Welcome to h2g2's attempt to decipher the mystery that is the song 'The 12 Days of Christmas'. You've come to the page that is concentrating on the line Four Calling Birds, and here's what our Researchers came up with when we asked them what on earth this line meant.

• For those of you with an interest in etymology, the term 'calling birds' in the song is a deviation from the original term 'colly' or 'collie bird'. 'Colly' means 'black' and came from the old word for coal, so the four colly birds in the carol are in fact blackbirds. This doesn't really explain why anyone should want to give their true love four blackbirds, but there's no accounting for taste...

• One Researcher suggested that this line refers to the quartet of telephone receptionists that you need to respond to all those people who forget to send you a Christmas card, then get one from you on Christmas Eve, feel guilty, and so call you up to wish you a 'Merry Christmas' in the middle of your favourite Christmas TV special. These days, of course, you'd just switch on the answerphone, but this is an old song, remember.

• Another angle is that this is a veiled reference to the dynamic rise of the 'new ladettes', the women who manage to turn the tables on new man and his pathetic foibles by whistling at men on building sites and drinking ten pints of lager before devouring a vindaloo curry... while still remaining attractive. It's the same glorious role reversal that's celebrated in the TV adverts for Diet Coke... or should that be Diet Bloke? We're not sure, but it's certainly worth singing about.