Yes it's ageist to say so, but as the guy is very close to my age I may as well point it out - Jeremy Corbyn is too old to be Labour leader. He's sixty-six and for some that would not be too old, but for Corbyn it is.
We know all about his left-wing credentials, his eccentricity and professional radicalism. We know about his lack of government and business experience, but his age is an important aspect of all that. He has had plenty of time to achieve something, hasn't achieved it and now it is too late.
The unexpected may happen, he may blossom, adapt and bring principles to modern politics, but the omens are not good. After careful examination of the entrails of a Norfolk crab and salmon tart, the runes suggest this is not likely to be the opportunity he has been waiting for all his life.
As far as one can tell he hasn't been waiting for an opportunity anyway. The sidelines have been his métier and that's where he belongs. No doubt he knows it.