Help - T.V play, farmer with cows called Gert, Daisy loses farm, does anyone know the name of play please?

Please can any of your fans tell me the name of a play which I rate as the best thing I have ever seen him in. He played the part of an old farmer in Wales who was persuaded by his sons and their computer models to vastly increase his dairy herd of cows and to borrow heavily to do so. Soon after, the EU imposed milk quotas, he locks the inspector in the muddy isolated calf shed and then loses everything - the farm having been in the family for generations. It ends with him alone in either a mental institution or prison with him saying "come on in, Gert, Daisy etc," (the names of the cows) which was so poignent as that was how the play started, but him in the field calling the cows in. I have searched for hours on the net, please help. Also does anyone know if it is available anywhere to purchase. Thanks very much.