With over 1800 people now slaughtered in Gaza, she tweets that she's now unable to support Cameron's ongoing overtures to Israel:
"With deep regret I have this morning written to the Prime Minister & tendered my resignation. I can no longer support Govt policy on #Gaza"Warsi also said the government's:
"approach and language during the current crisis in Gaza is morally indefensible, is not in Britain’s national interest and will have a long term detrimental impact on our reputation internationally and domestically".This is all good for the Palestinian cause. And well done to Warsi for taking such action - might others now reflect on putting their careers before speaking out about Gaza and other such crimes?
Boris Johnson has also condemned the killing, though still in terms of its negative impact on Israel:
"I am a passionate supporter of Israel. I cannot for the life of me see the purpose of this. It is disproportionate, ugly and tragic and will not do Israel any good the long run."But seeing such senior figures worry and resign is indicative of how much the establishment now recognise a dangerous writing on the wall for Israel, and, most crucially, the gathering public mood.
Consider also how Miliband has decided to put Cameron 'on the spot' over Gaza, just as he opted to oppose the bombing of Syria. All of this comes after carefully weighing the strength of public feeling and evaluating whether it's worth the political risk.
Warsi's resignation should be seen in the same essential light.
Her departure and ostensible reasons for it - the humanitarian cost - are less notable than what it says about the gathering public awareness over Israel's criminal standing.
And that has all come from a bottom-up process, driven by the current outrage over Gaza and a more sustained level of social media-led campaigning.
In other words, the political stirrings we're seeing, even among senior Tories like Crispin Blunt - calling Israel's actions "war crimes", and even suggesting punitive sanctions - is a barometer of how seriously world feeling is now pushing against Israel.
As a Muslim, Warsi is well aware of the sensitivities of being part of a government so deeply involved in backing and arming Israel. Now free from the bonds of office, she has spoken more openly, calling for an arms embargo against Israel and regretting that the UK failed to support the Palestinian application for statehood at the UN.
So, why didn't she say all these things before? Gaza has been under siege for eight years now, subject to murderous attack every day, including deliberate violations of the 2012 ceasefire.
Again, it's that same political calculation. Political elites may hold real humanitarian concerns and misgivings, but all that can sit in career safety so long as no major event brings it into public focus. Gaza has now done that for Warsi.
The tipping point is coming for Israel. And when the day of reckoning comes, as it did for South Africa, many, like Warsi, will not want to be remembered for being on the wrong side of history.
A comment in an earlier version of this text was erroneously attributed to Baroness Warsi, rather than Boris Johnson. Now corrected.