If you had to name a list of the most cravenly loyal Labour MPs of the last decade Barry Sheerman would be near the top of it.

Throughout the Blair years the long-serving chairman of the Education Select Committee could be relied upon - whether in the Commons or on the broadcast media - to come to the aid of the party. No more.

Nowadays Mr Sheerman - to virtually everyone's surprise - has become the focus of what remains of the "Brown must Go" tendency in the Parliamentary Labour Party. He has not himself called directly for the Prime Minister to depart but, when asked, he has regularly raised doubts about his future.

In recent weeks he has let it be known that he is thinking about standing for the chairmanship of the PLP. He would have little chance of winning against the incumbent Tony Lloyd but it has been put round that MPs voting for him would, as a proxy, really be voting for the ousting of the Prime Minister. He has yet to make a decision whether to run.

So has this anything at all to do with today's outburst by Mr Sheerman against Ed Balls after the latter turned down his committee's rejection of his choice as children's commissioner?

The answer is almost certainly yes, although neither will admit it. Mr Sheerman called Mr Balls a bully - probably not unparliamentary language but tough stuff all the same. And it would not be surprising if the sharpness of the words had something to do with the fact that before, throughout and beyond the Blair government, Mr Balls has been Mr Brown's closest ally, the man reputedly behind the independence of the Bank of England and much else that happened during Mr Brown's Treasury years.

In those years, when Numbers 10 and 11 often seemed at war, Mr Balls was one of the least popular figures among the Blairites, of whom Mr Sheerman is a fully paid-up member. Senior figures who worked in Number 10 frequently complained about the way they were treated by the combative Mr Balls.

So in attacking Mr Balls Mr Sheerman may also have been - again by proxy - attacking the Prime Minister and his style of government. True they have had their differences over education as well, as Mr Sheerman was at pains to stress this morning, insisting the row was nothing to do with the PLP chairmanship. But to the practised ear of any Labour MP listening to their radio early this morning, this was personal. Mr Sheerman may have picked up a few votes if his bid for the PLP goes ahead. But he will have made some enemies as well.

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