Chris Moncrieff: Watch out, Jezza! Your biggest rival is sitting to your left (where else?)
The Shadow Chancellor's political abilities tower above those of his Labour colleagues ... pity he wants to overthrow capitalism
Does the real threat to Jeremy Corbyn sit alongside him in the House of Commons, rather than facing him from the Conservative benches? Because, when it comes to political skills and acumen, Shadow Chancellor John McDonnell stands head and shoulders above any of his colleagues - Corbyn included - in the wishy-washy Shadow Cabinet.
Let us consider some of its most prominent members: Corbyn himself shows no great leadership qualities and his parliamentary contributions do not set the chamber alight; Shadow Home Secretary Diane Abbott can't add up; Shadow Brexit Secretary Sir Keir Starmer talks in incomprehensible, legalistic riddles.
So, there is not much competition there to trouble McDonnell, who is forthright and honest about his political ambitions, which are, he says bluntly, the overthrow of capitalism.
The idea that he might want to boot Corbyn out of his job may sound preposterous and, anyway, the difficulties in dumping a leader, who is determined to hang on, are immense. But it is not impossible.
Remember: who on earth would have predicted that Corbyn could become Labour's leader? So, to employ the old cliche: watch this space.
Labour have not been effective either in challenging the government's performance, even though Theresa May's administration is itself in a state of disarray.
What is more, there is more squabbling in the Cabinet, with Environment Secretary Michael Gove blaming Chancellor Philip Hammond for the defeats over Brexit in the House of Lords (dinosaurs in ermine, as described by the Daily Mail).
All this civil war and incompetence is good for newspapers, but bad for government.
Will these people never learn?
The issue of Labour's all-women shortlists at election times has come to the fore again. Apparently, people who have changed sex to become women will be allowed on them. Big deal.
But the whole idea of such shortlists is questionable, to say the least. They are insulting to women, an affront to would-be male candidates and unfair to potential Labour voters, who would surely expect their candidate to be chosen not just from one section of society.
What is more, the very people who condemn sexism (and the other -isms, too) are the very ones endorsing it in this way. It is hypocrisy writ large.
I cannot understand how any self-respecting woman could demean herself in these circumstances.
The whole practice should be abolished - and without any delay.
The botched and shambolic introduction of new rail timetables by some leading train companies has led to a sharp increase in the clamour for the re-nationalisation of the network. This, plus the crisis on the East Coast mainline route, has surprisingly led even some Conservative MPs to believe that the railways would benefit by being returned to public hands.
Parliament and, more importantly, the rail travellers are becoming increasingly - and justifiably - frustrated and angry about the performances of some of the rail companies.
Admittedly, unlike a royal wedding, you cannot have a dress rehearsal for a major overhaul of the timetables.
Even so, the rail bosses seem to have embarked on this major event without any serious forethought on how it should be implemented. One trusts that things will improve, but the auguries are not good.
The rail companies boasted of more trains than hitherto - but the initial evidence seemed to show actually fewer trains and cancelled trains, with hundreds of fuming passengers stranded on station platforms.
The state has now - and not for the first time - taken over the important East Coast route because the companies involved could not make it pay. Transport Secretary Chris Grayling may well be tempted to look critically at some other parts of the network.
Meanwhile, it would do no harm for someone to take a look at the operation of the fast, immaculate and punctual railway system in Japan.
Things cannot go on as they are in this country. Rail travellers are paying ever more in fares as the system slowly, but discernibly gets worse.
Something a lot more drastic than a slap on the wrist is called for.
Roman Abramovich, the Russian billionaire owner of Chelsea Football Club, is facing problems renewing his UK visa.
Some suspect this is a deliberate Home Office ploy in the war against "dirty money", although there is no evidence that Abramovich has broken the law in any way.
But since Abramovich is very close to Vladimir Putin and since Russia is in a tit-for-tat mood, what if the Kremlin suddenly denied Russian visas to the England football team preparing for the World Cup?
Now that would cause an almighty storm.