M4 relief road: Prof Garel Rhys and wildlife trust boss Tom Clarke discuss

Chancellor George Osborne is expected to announce plans in his comprehensive spending review at the end of June for an M4 relief road in south Wales.

He has described it as one of the most important road schemes in the UK.

On Radio Wales' Sunday Supplement, Prof Garel Rhys, a motor industry economics expert at Cardiff Business School, and Tom Clarke, chief executive of Gwent Wildlife Trust which has opposed the idea of a relief road, debate the merits of such scheme with Vaughan Roderick.