Ed Balls, the Shadow Chancellor. The title of the conference is "The Economic Alternative" - and the full programme is available here.
The Fabian Society has been influential in the Labour Party throughout the party's history. The "Fabians" played a key part as one of the organisations which set up the Labour Party. Originally formed in 1884, it was a "think tank" long before the term became fashionable. It takes its name from the Roman General Fabius Maximus, whose strategy was to avoid the immediate headlong attack - but to adopt a longer term "gradualist" approach - which delivered ultimate victory more effectively. That describes the political strategy of the Fabians. They oppose violent revolution - but the establishment of social democracy through persuasion. I once owned their tie which was a succession of the phrase "the inevitability of socialism".
The photograph is of George Bernard Shaw, the playwright, one amongst many influential Britons who have been involved in the Society. A book he wrote on the early history of the Society is available here.