Professor Ben Green FRS has won the Royal Society's Sylvester Medal for his result on primes in arithmetic progression, and his subsequent proofs of a number of spectacular theorems over the last five to ten years. The Sylvester Medal is awarded biennially (in even years) “for the encouragement of mathematical research”. The award was created in memory of the mathematician James Joseph Sylvester FRS, who was Savilian Professor of Geometry at the University of Oxford in the 1880s. It was first awarded in 1901. Originally it was awarded triennially, but from 2010 it is now awarded biennially in even years.