"There's no point trying to shout me down" shadow defence secretary Emily Thornberry declared midway through tonight's Parliamentary Labour Party meeting. Even by recent standards, the 70-minute gathering was remarkably fractious (with PLP chair John Cryer at one point threatening to halt it). Addressing MPs and peers for the first time since replacing Maria Eagle, Thornberry's performance did nothing to reassure Trident supporters.

The Islington South MP, who voted against renewal in 2007, said that the defence review would be "wide-ranging" and did not take a position on the nuclear question (though she emphasised it was right to "question" the £31bn renewal). She vowed to listen to colleagues as well as taking "expert advice" and promised to soon visit the Barrow construction site. But MPs' anger was remorseless. Former shadow defence minister Kevan Jones was one of the first to emerge from Committee Room 14. "Waffly and incoherent, cringeworthy" was his verdict. Another Labour MP told me: "Risible. Appalling. She compared Trident to patrolling the skies with Spitfires ... It was embarrassing." A party source said afterwards that Thornberry's "spitfire" remark was merely an observation on changing technology.

"She was talking originally in that whole section about drones. She'd been talking to some people about drones and it was apparent that it was absolutely possible, with improving technology, that large submarines could easily be tracked, detected and attacked by drones. So she said it is a question of keeping your eye on new technology ... We don't have the Spitfires of the 21st century but we do have some quite old planes, Tornadoes, but they've been updated with modern technology and modern weaponry."

Former first sea lord and security minister Alan West complained, however, that she had failed to understand how nuclear submarines worked. "Physics, basic physics!" he cried as he left. Asked how the meeting went, Neil Kinnock, who as leader reversed Labour's unilateralist position in 1989, simply said "yeah" and let out a belly laugh. Labour MP Madeleine Moon, a defence select committee member, tweeted: "Oh dear oh dear omg oh dear oh dear need to go rest in a darkened room." Thornberry herself stoically insisted that it went "alright". But a shadow minister told me: "Emily just evidently hadn't put in the work required to be able to credibly address the PLP - totally humiliated. Not by the noise of the hecklers but by the silence of any defenders, no one speaking up for her."

Richard Burden said the issue was not a "binary" one (perhaps having in mind the possibility of avoiding full renewal) and that neither side had a "monopoly of wisdom" on how to maintain security. But Barrow MP John Woodcock, who has launched his own rival Trident review, noted that Ed Miliband had examined the issue in the last parliament and that "even he" couldn't find an alternative to four new Trident submarines. Former shadow cabinet member Caroline Flint warned that opposing renewal would be a "disaster" and declared: "Jeremy's made up his mind, hasn't he?"

Labour has long awaited the Europe split currently unfolding among the Tories. But its divide on Trident is far worse. The majority of its MPs are opposed to unilateral disarmament and just seven of the shadow cabinet's 31 members share Jeremy Corbyn's position. While Labour MPs will be given a free vote when the Commons votes on Trident renewal later this year (a fait accompli), the real battle is to determine the party's manifesto stance.

Thornberry will tomorrow address the shadow cabinet and, for the first time this year, Corbyn will attend the next PLP meeting on 22 February. Both will have to contend with a divide which appears unbridgeable.