Tom Collyer, a PhD student from the Mathematics Institute, has won the Times National Su Doku Championship for the second time - making him one of only two people ever to win the Championship more than once. Ranked as number 26 in the world, Tom arranged 324 numbers into 4 Su Doku grids in just 17 minutes to take first place.

More than 100 amateur logicians were shortlisted for this year's championship, out of a record 770 entrants. To qualify for the final, competitors had to fill out four fiendish Su Doku grids in an hour's session and were then ranked by speed. Once completed, sheets were checked for accuracy and points were deducted for errors. After two rounds, the remaining eight contestants sat the grand finals at the Institute of Education in London.

"They were noticeably harder this year but that plays to me," said Tom. "There was a point at which I was stuck but my guessing technique is shambolic. So I didn't guess."

Tom's victory won him a cup and £1,000 in prize money which he may use to enter the US Su Doku Championships in Philadelphia.