After 24 years as a correspondent, Foreign Affairs Editor & Diplomatic Editor at Sky News, award-winning journalist Tim Marshall has used his experiences to write best-selling books using maps of crucial regions to explain the geo-political strategies of world powers. 

Tim - who is commentating on the situation in Ukraine and writing for publications like The New Statesman - explains why he thinks this conflict is the best example in the world of geography being a determining factor.

He tells Helen there's been an outpouring of need for context in what he describes as a 'watershed moment' in our history - from both a detailed level on the ground and a bird's-eye view of why this is happening and the deep background & history to it all.