Ffynone House School pupil James Arthur has won the 15th annual Cipher Challenge beating more than 15,000 other competitors.
James, 15, received his award at Bletchley Park, the World War Two code-breaking establishment.
In year 11 at Ffynone James was not only one of the youngest entrants but he entered the competition as an individual whereas some of the prize winners were groups.
“I was very proud to win because I did it on my own and therefore thought I had no chance,” said James, who lives in Swansea but comes from Cornwall.
“It was a shock that I’d won on my own when there were groups of five, six and seven people,” said James, who received a rucksack and a signed book.
‘’It was full on brute force to break the codes.”
James has been taking the challenge ‘religiously’ since he was in Year 7 and is already getting ready for next year’s challenge.
Ffynone head teacher Michael Boulding said the whole school had been very impressed with James’s success.
“What James has achieved is hugely impressive and he should be very proud of his achievement especially as the competition is open to students three years his senior,” he said.
James says that he has ambitions to be a code breaker when he finishes education.
He said: “I would love to work with GCHQ. They probably already know me because they like to write down everybody’s name down. They have huge data bases so I’m sure I’m on one of them!”