As if there wasn't enough Doctor Who anniversary fun this year, today we reach another milestone. It's five years since we first met Alex Kingston's lovelorn archaeologist River Song, and the phrases "Hello sweetie" and "Spoilers" became instant catchphrases. The show's official Twitter feed has declared it #RiverSongDay and there's a flurry of activity going down at the BBC's Doctor Who site.

River has been more divisive than almost any other character in Doctor Who history. Regular visitors to this blog will know that my love for her is unending. Her combination of lavish camp, gun-toting badassery and desolate heartbreak makes her my perfect woman.

Not everyone agrees. Some fans find River too smug and theatrical. Kingston has attracted criticism for vamping it up just a bit too much – something that was becoming a problem around the time of Let's Kill Hitler, and has, thankfully, been dialled down since. In addition to this, her story was at the centre of the divisive season six/32. The ongoing plot that would reveal her as Amy and Rory's daughter, kidnapped and brainwashed to kill our hero, was a bold and intricate development, but it gave rise to accusations that the show was becoming too complicated, which in turn became a stick haters used to gleefully beat the show.

But most of all, River's detractors are the people still clinging to the notion of a sexless Doctor, a noble hero above such human fripperies as love. That seems to me the most curious argument of all. At every stage, his reaction to every advance has been one of awkward confusion. The relationship was never tenable, and not just because she could drive the Tardis better than him. Around her, he became impish and petulant. "When one's in love with a lonely god," she told Amy last year, "one does one's best to hide the damage." And there is precedent for romantic involvements. Back in the old days, the Doctor was devastated when Jo Grant left in The Green Death, and the 10th Doctor's relationship with Rose became a romantic tragedy by the end. Yet even though River has been doing all the chasing, and the Doctor she "married" was actually the Tesselactor robot, she has been the most obvious conduit for the character's steady shift towards love.

In the stunning recent series finale, everything changed again. The River we met this time was post-Library, a manifestation of her consciousness brought to life through Vastra's "conference call". When faced with the question of why he never went back to the Library, the Doctor said: "I thought it would hurt too much." A trembling River replied: "I believe I would have coped." But that was not what he meant. "I thought it would hurt me," said the Doctor, "and I was right."

Quite apart from the big John Hurt revelation, that devastating send-off was something else completely new. The Doctor publicly declared love for a woman, and initiated the kiss himself. It's a development that has led many people to predict that this was Kingston's final appearance, their romance given its tragic end. The BBC, of course, will reveal nothing, and while there are plenty of ways to bring River back, at whatever point in her timeline, the poetry of it would suggest that scene could well have been her swansong.

So, this #RiverSongDay, let's take the chance to salute this precocious buccaneer. Let us know where you stand in The Great River Debate. Tell us your favourite moments. And what do you think really happened that night they met Jim The Fish?