"The 'old Brownites' - including Ed Balls, Damian McBride and Ian Austin - are Labour tribalists who think the way to victory is through class war. Personally, they are laddish, football-loving street fighters. Politically, they are ruthless in the way they operate, demanding absolute loyalty (to Mr Brown, rather than to Labour) in return for favours.
Having honed their skills creating dividing lines with Tony Blair, now they want to fight a highly personal campaign against David Cameron, portraying him as an Old Etonian toff. In policy terms, they want to emphasise equality of outcome as well as of opportunity.
Mr Carter is the leader of the 'New Brownites' who argue that there is no point in creating a dividing line if the voters are on the other side of it. The New Brownites are not of the Labour tribe, but in their view this is no time for the party to be tribal.
The new Downing Street appointees have joined forces with Cabinet ministers including James Purnell, Tessa Jowell and John Hutton to push the Prime Minister to go further, faster on public service reform and to beware of further increases in taxation.
They dislike the class warfare against Mr Cameron, because they think it looks chippy. Their aim is to find a language that appeals to Middle England as well as the Labour heartlands - Mr Carter has been asking visitors to Downing Street whether 'talent' is a better word than 'aspiration'. For them, excellence matters as much as equality."
Sylvester thinks that this split is actually more significant than the old Blairite-Brownite dividing line. It will be fascinating to see if Gordon comes down firmly on one side or the other of this dispute, or continues to flit between the two approaches as he has in recent weeks.