The world's hardest sudoku - solved

Yesterday we printed the "world's hardest sudoku", created by Finnish mathematician Arto Inkala. Here's the solution. And if you completed the puzzle, did you do as well as William Brown of north London, who called the G2 office on Monday afternoon? Brown solved it in two hours, while baking bread, and made just one mistake, which he rectified. So, how did you get on?