I'm a big fan of Iolo Wiiliams and whilst he is a talented broadcaster and top naturalist, he's an even better public speaker.
Its well worth watching him lay into the politicians and civil servants at the State of Nature launch of 2013. The suits invited him along to speak, probably hoping he was going to pat them on the back and 'say the right things' instead he launched into a 15-minute masterpiece of oratory during which he slated them for the state of the rivers and countryside of Wales and publicly shamed them. We need more like him.
PS - the Welsh stops after 30 seconds!