document: Judith Kerr's children's book sold 72,935 copies in the last week, according to Nielsen BookScan.
  It makes it the 10th consecutive week a children's book has taken the number one spot, while four out of the top five books are children's titles.
  Diary of a Wimpy Kid: Old School by Jeff Kinney is at number two, with David Walliam's Grandpa's Great Escape at three.
  Kerr published 16 Mog books with Mog's Goodbye released in 2002, in which Mog died.
  She brought Mog back to life for Mog's Christmas Calamity, which is also the subject of this year's Sainsbury's Christmas advert. It sees the accident prone cat causing havoc with the Thomas family's Christmas.
  First number one
  The book is being sold by the supermarket chain and all the profits for the book are going to Save the Children. It has raised nearly Â£900,000 for their UK child literacy campaign so far.
  Despite a highly successful career, Mog's Christmas Calamity is Kerr's first number one book. It also makes Kerr the oldest person to top the book chart.
  Mog's Christmas Calamity sold 74,453 copies in its first three day of sales and has outsold all previous Mog books.
  Its first week sales were the highest for a children's book since J K Rowling's Harry Potter spin-off The Tales of Beedle the Bard in 2008.
  It is the third book in the year to have sold more than 100,000 copies in one week, after EL James's Grey and Harper Lee's Go Set a Watchman.
  It is only the second picture book to go to number one in 2015 after McFly members Tom Fletcher and Dougie Poynter's The Dinosaur That Pooped a Lot.
summary: Mog's Christmas Calamity has topped the UK book chart for a third week.