Andrew Harrop, Fabian Society general secretary said:
The Fabian Society is devastated to hear of the tragic loss of our friend Jo Cox, Labour MP for Batley and Spen. Our thoughts are with Brendan, their children and all her friends and family and we send them our deepest condolences.
During her short time in parliament, Jo made a huge contribution to Labour politics and to speaking up for the victims of war, including writing an outstanding chapter in a recent Fabian Society book.
Jo was a brave and passionate politician who left the world a better place. She was an inspiration to young women. Everyone at the Fabians will miss her greatly.