The fair capitalism debate that has rumbled on throughout this week looks likely to continue into the next one.

Business Secretary Vince Cable is delivering a speech on Tuesday on the subject of executive pay. (The coalition thinks some of it is too high, or rather, it isn't adequately indexed to commercial success.) Cable is speaking at an event hosted by the Social Market Foundation think tank, although Chuka Umunna, shadow Business Secretary, is trying to force Vince to announce his plans in parliament first. Umunna raised a point of order with the Speaker on Wednesday on the grounds that it is - as John Bercow has himself made clear in the past - bad form for ministers to bypass the House when presenting new policy.

It's a small point, but then parliamentary point-scoring is one of the few ways the opposition can have any impact at all. Trying to make Cable give an account of himself in parliament is a sensible tactical gambit since the Commons chamber is always a less forgiving environment than, well, anywhere really. Especially for Lib Dems.

Cable is quite a threat to Labour on this topic. His speech to the Lib Dem party conference last year covered a lot of the themes that are now established in the cannon of "responsible capitalism" rhetoric. And that was a week before Ed Miliband made his famous (at least to political obsessives) predators v producers speech at the Labour conference in Liverpool. Committed students of Vincology will know that his book - The Storm - concluded with a call for conscientious liberal reforms to capitalism in order to head off a populist attack from the far left and far right in the aftermath of the banking crisis.

Cable is also the only politician who can out-boast Ed Miliband when it comes to standing up to Rupert Murdoch - it is a badge of honour they both sport ostentatiously as evidence of their willingness to take on "vested interests".

As I wrote in my column this week, the Lib Dems badly need to be associated with something popular that the coalition is doing. Bashing bankers - a topic on which Vince has form - very much fits that bill.

The Tories, meanwhile, are playing a slightly different game. They are motivated chiefly by the need to close the "fair capitalism" subject down as a political playground for Ed Miliband. As I wrote in the column, Downing Street thinks it has enough material on responsibility and fairness in the Cameroon archive (going back to the brand decontamination "modernising" days) to persuade people that the prime minister has been into this stuff for years and that, by extension, it is not the exclusive property of the Labour leader.

But I now gather there is more to the strategy than a simple policy wardrobe raid. People close to Cameron are persuaded that Miliband's instincts are substantially to the left of his public pronouncements. The thinking in Number 10 is that, with a bit of pressure for ownership of this new centre ground, where it is fashionable to decry the ugly side of capitalism, Miliband can be nudged into a more fundamentalist stance. Part of the thinking behind Cameron's "moral markets" speech yesterday was to draw a dividing line between those who want capitalism to work better and those who think it is really a scam from top to bottom, with Labour on the wrong side. Cameron and Osborne want to maneouvre the Labour leader into a position where he sounds not pro-reform but anti-market. The Tories don't just want to expropriate Miliband, they want to drive him off into a tent by St Paul's.