It's an inspiring article, but it left me wondering what is his exit plan. He's got nobody to pass the farm on to, and his sister is dependent upon his care. At 72 and with his medical history, he will not be able to continue much longer.
This is in the UK where there exists something of a social safety net. For example, I very much doubt he pays for his sister's carers (speaking from experience), and he will have healthcare available for himself if he needs it. So he may not feel the need to consider an exit plan.
He never married, presumably has no kids, so what happens to the farm after he's gone probably isn't a big concern of his.
My understanding is that in the UK if you have no heirs your property reverts to the crown.