Two's up!
Corbyn is so very obviously not up to the gig of running the country, when we consider that he has shown himself not up to the vastly simpler task of running the parliamentary Labour Party.
But in that parade of the chronically incompetent, I would have to include May an Co. and her hapless predecessors Blair/Brown and Cameron/Osborne. The last time a competent Chancellor of the Exchequer took office in Westminster was probably Sir Walter Mildmay under Elizabeth the First. He died in office in 1589 and it's been downhill ever since!
@The Byre, you make good points, but .... greater equality leads to growth?!
I'm not a big fan of greater equality .... nor do I subscribe to the view that it inevitably and always leads to growth.
But it does!
In my work as a policy wonk for a UK political party, I researched this and other subjects to death!
We asked the question - Is an unfair society overall richer or poorer? Numerically and nominally - yes. The evidence is overwhelming. Doubling the Gini index will actually halve the GDP-per-capita. However, once you factor in the cost of living, this effect is halved, i.e. doubling the Gini-index will reduce the GDP-per-capita by 25% and not 50%.
Other factors we looked at were education (huge effect of past spending!) and size of country (another huge effect - small is beautiful!)
We only looked at N.W. European countries, as these have been living under the same trading conditions for 50 years and are sufficiently free of corruption to be comparable. The EU has given us a magnificent 50-year experiment in macro-economics like no other in history!
We did discover (but did not go as far as to put numbers on this) some of the effects of taxation. High taxes are a great way to achieve greater equality, but have a detrimental effect on wealth. It appeared that achieving greater equality by taxation alone was a 'zero-sum-gain' i.e. the end effect was to cancel itself out and may possibly have a long-term negative effect.
Simply put,
an increase in taxation always increases the cost of living.
Some taxation is inevitable, but it is far, far more beneficial to achieve greater equality and the alleviation of poverty by legislation, such as rent-control, minimum wages, employment protection, mandatory care-insurance, stuff like that. Unfortunately, as one cannot put a number on legislation, we did not pursue these effects down to the level of being able to quantify them, but the correlation of social laws and standards of living and overall wealth in counties such as Denmark, Germany, Benelux group, Sweden, etc. sticks out like a sore thumb!