Military Wives single is 'fastest selling in six years'
The Military Wives Choir looks certain to have the Christmas number one, after becoming the fastest-selling single in six years.
The Official Charts Company said 319,000 copies of the choir's song, Wherever You Are, were sold by midnight on Tuesday.
The company said it was "an extraordinary result".
The single is outselling nearest rival, Cannonball by X Factor winners Little Mix, by a margin of six to one.
The song by Little Mix, the first group to ever win the X Factor, topped the charts on Sunday.
Last week Little Mix sold 210,000 copies of their Damien Rice cover record, considerably lower than previous X Factor winners.
The Official Charts Company said 242,000 copies of Wherever You Are were sold in two days, making it the fastest-selling single in six years.
The last time a single sold so well in its first two days was when X Factor winner Shayne Ward shifted 313,000 copies of That's My Goal in 2005.
The Treasury has announced it will waive the VAT on the Military Wives single, by making a equivalent donation to the charities benefiting from its sale.
Chancellor George Osborne said: "Our armed forces demonstrate incredible commitment to the nation and make sacrifices for all of us.
"The Military Wives choir is doing a great job of raising money for this hugely worthy cause.
"We will donate the tax collected on the single so that as much as possible of the money spent by the public on this fantastic song goes to charities helping our armed forces and their families this Christmas."
The single originates from the BBC Two programme The Choir, which saw Gareth Malone create a choral group from the wives and partners of military personnel who have been deployed to Afghanistan.
The lyrics of Wherever You Are were taken from love poems, which were written between the women and their absent husbands.
Royal Wedding composer Paul Mealor wrote the music.
The choir performed the song at the Royal British Legion's Festival Of Remembrance earlier this year.
The track has become the fifth fastest selling single since 1994, when sales were first tracked.
The fastest selling single is Elton John's Candle In The Wind, which was released in 1997.
Some bookmakers have stopped taking bets on the Christmas chart outcome.
It means the X Factor could be denied the festive top spot for the second time in three years - after Rage Against The Machine beat Joe McElderry to number one in 2009.
The show's creator Simon Cowell congratulated Malone and his choir, tweeting: "Congrats to Little Mix & congrats to Military Wives. It's a great cause & a worthy Christmas No.1."
Other contenders for the official Christmas number one this week include Lou Monte's Dominick The Donkey, two different versions of Last Christmas and Stacey Solomon's rendition of Driving Home For Christmas.
Proceeds from the sale of each Military Wives CD will be donated jointly to The Royal British Legion and the Soldiers, Sailors, Airmen Families Association.