Matt Baker and Julia Bradbury head for Hadrian's Wall in Northumberland to get a sneak preview of a spectacular plan to light all 73 miles of the iconic landmark as part of its 1,600th anniversary celebrations. Elsewhere, John Craven investigates why culling certain species of animals can help to conserve others and asks if the costs outweigh the benefits. James Wong looks at the future of food production and examines whether vertical farming - growing food on walls - could help feed our cities, while Adam Henson is hoping spring has finally sprung down on the farm when he scans his ewes to see how many lambs he can expect this season.