James May carries on with his mission to show what is possible with old-fashioned toys by using them on a scale never seen before. This week, he moves from the world of plasticine to that of Meccano, joining forces with novelist and broadcaster Edwina Currie (of all people) to build a full-size bridge. A collection of talented engineers pitches incredible designs, but James finds himself delayed when the materials fail to turn up on time, and things go from bad to worse when a last-minute accident means that James's bridge may never see the light of day. Thankfully, May can articulate his disdain, instead of waggling his tail like an irked cat, or banging his chest like a baboon. Why can humans communicate through speech, anyway? Perhaps Horizon's Why Do We Talk might have some answers to that question (9.00pm, BBC2).