By Giles Edwards
Producer, BBC Radio 4's Decision Time
How do backbench MPs persuade ministers to change their minds?
They try often enough. But bearing in mind how often big rebellions take place, we know very little about what is going on behind the scenes.
Now one prominent backbench organiser - Labour MP Martin Salter - has broken his silence for Radio 4's Decision Time programme, which discusses how a future government might cut middle class benefits.
Martin Salter is the man who organised the huge rebellion over the Education White Paper in 2005. He ended up sitting over the table from Tony Blair and said, "Prime minister, I think it is time we talked."
How did he get to that point?
His first maxim is borrowed from the American President Theodore Roosevelt: "Speak softly and carry a big stick."
To do that, he says, "you need to assemble your big stick, and your big stick is about numbers".
That means finding MPs who might join his rebellion.
Martin Salter is candid about the tough tactics he would use to persuade Labour MPs: "What I would do is initially start to shoot the messenger. I would be looking at where did these ideas come from."
Next is another set of numbers. This time, he would be trying to uncover the Treasury's distributional analysis, which is essentially a 'scoresheet' on who would win and lose from the policy being proposed by the government.
Listen to the full programme on BBC Radio 4 at 2000 GMT on 13 January 2010
That information, he says, would be crucial to the second part of his tactic, which is reaching beyond the habitual rebels to more mainstream MPs.
This, he argues, is all about being reasonable, and looking for areas they could agree with their government.
That might mean accepting some of what is being proposed, but he would be brutal with other parts of the package.
He says one tactic is salami-slicing the proposals - reframing the debate to reject those which would harm the interests of the poor.
This would help define his negotiating position, but it would also have another benefit. Arguing that the poor should not have their benefits cut to pay for tax cuts over recent years "would work well on the backbenches and enable us to galvanise mainstream opinion", he insists.
If he needed some polling about what the policies would mean in marginal seats, or to come up with some alternatives, he might work with an outside body like the think tank Compass.
But he would also work with people inside the government. Divisions between ministers would offer some particularly fertile territory.
"I would seek to get a dividing line in there between the reluctant Cabinet minister
and some of the more extreme policy wonks in Number 10 who are pushing forward this agenda, without due regard to the core Labour vote," says Mr Salter.
This was exactly what happened in 2005 over the Education White Paper, when he noticed that the two forewords to the document - one from the prime minister and one from the education secretary - said very different things.
"Game on," says Mr Salter pithily.
All of this sets the rebels on a collision course with the government, but what happens when the time comes to settle the disagreement?
Martin Salter was a trade union organiser before he became an MP, and is blunt about the end result he wants.
"I don't start from the premise that a backbench rebellion is somehow glorious - I think if you end up voting against your own party it is a failure, and it is a failure on all sides," he says.
So while he is pushing ministers into a corner with one arm, he is ready with an exit strategy in the other, just as he did over the Education White Paper. What would that consist of?
A deal, of course.
"I would say to the prime Minister 'yeah, if you would modify the proposals in this dimension, I think there is a chance that those of us that have been organising opposition to this could recommend to people that the government have moved and acknowledge those concessions, both in the way we speak on the run-up to the debate and the way we cast our votes'."
But, he insists, "those red lines would have to be met."