Jk Rowling has been known to enjoy letting Harry Potter fans in on some new information about their favourite characters, but on Saturday the author used a little bribery to drum up support for Scotland in the Rugby World Cup from her loyal followers.

JK RowlingJK Rowling has revealed the birthday of Sirius Black.

As Scotland were gearing up to face Samoa, Rowling asked fans on twitter to show their support, promising to then reveal the birthday of Sirius Black if enough people tweeted the hashtag AsOne.

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‘Off to Newcastle for #SAMvSCO and if lots of you tweet #AsOne to support Scotland, you can have Sirius's birthday! #RugbyWorldCup,’ Rowling tweeted. As the author nervously watched the game live she kept her followers informed on twitter as they showed their support.

‘Samoa 26 Scotland 23 and I feel queasy. #AsOne,’ Rowling tweeted during the game. ‘Scotland 36 Samoa 26 and I'm losing my voice #AsOne,’ she added, as her beloved Scotland took lead.

When all was said and done Scotland narrowly clinched victory, winning 36-33 and of course Rowling kept her word. "WE WON!!!!!! And Sirius Black was born on the 3rd of November xxxxxxxx,” the author tweeted once the game ended.

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Black is one of the most beloved Harry Potter characters and was played by Gary Oldman in the film franchise. He was a pure-blood wizard and the cousin to the evil Bellatrix Lestrange, but Black was also a close friend of James Potter in school and became Harry’s godfather. He sadly dies in the series’ fifth book, Harry Potter and the Order of the Phoenix.