There's a particular form of argumentative reasoning that's dubbed a 'motte and bailey strategy' and it works like this:
A motte-and-bailey is an old form of medieval defensive system. The motte was a raised area of earth surrounded by a stone wall, whilst the bailey was a larger, but more weakly defended, area in front of the motte. As a rhetorical strategy the motte contains a true, but trivial, claim that a person can retreat to in a argument if their bailey argument - the one they want to make, but the one that is shakier as it's a more outlandish and extreme claim.
Recent discussion in the UK on the subject of opposition pressure operate according to this principle:
Bailey: Corbyn is useless and its only thanks to brave Conservatives that thing x is being stopped.
Motte: Labour doesn't have a majority, so only Conservatives rebelling could have stopped thing x.
The second is true, but also trivial. This is standard stuff about the mathematics of majorities in the House of Commons. The first, however, is making a stronger claim -- namely that it is only because of Conservatives following their own hearts that they're rebelling, nothing to do with opposition pressure whatsoever. That claim is wrong, or at the very least much harder to defend, hence why there's so much stampeding to the motte.
The particular impetus for this is the NIC U-turn that Hammond has announced, but note that this is nothing new. After all, how was it portrayed with Osborne u-turned over tax credits? Was it pressure from the opposition spooking Conservatives into changing their minds? No it was brave Tories, concerned about the impact on the common folk challenging their leadership. It was wise George Osborne recognising his mistake and changing his mind. When the government u-turned over the prison deal with Saudi Arabia? Michael Gove, with his wise wisdom and stern love of liberalism, was the hero of the hour.
And when Article 50 was voted through, with all amendments being voted down, was the story about cowardly Conservatives refusing to defy their government, showing no concern for what damage they might do to people's livelihoods or using EU citizens as bargaining chips?
Of course it wasn't.