Could Britain feed itself? Tom Heap assesses how much more of our own food we could potentially produce. Currently we import nearly half - 30% from the EU but in a time of growing population and political change could we step up our home grown fare? He asks about the innovative technology helping farmers make smart use of the land they have, visits labs to ask what changes we might need to allow and sizes up our allotments, gardens and window boxes to see if we could be more productive at home. With some theoretical ideas and practical realities he aims to give you food for thought. Producer: Anne-Marie Bullock