Complex sentence: Before that, he was the director of Policy Network, an international progressive politics thinktank and a senior visiting fellow at the Centre for the Study of Global Governance at the London School of Economics.
Split into simpler sentences: Before that, he was the director of Policy Network, an organisation that describes itself as'an international progressive politics thinktank'. He was also a senior visiting fellow at the Centre for the Study of Global Governance at the London School of Economics.