The direct impact of Michael Fallon’s resignation on the government’s stability is likely to be limited.
He went voluntarily, and the manner of his exit means that any resulting disruptive behaviour will be viewed deeply unsympathetically.
His Sevenoaks seat is, meanwhile, ultra-safe so even in the highly unlikely event of a by-election, disruption to the government’s business is unlikely.
There are however two significant and important knock-on effects which may have more serious repercussions on the government. The first is that Fallon has set the bar that any minister found to have participated in inappropriate behaviour must quit. The offence to which the former Defence Secretary has admitted happened 17 years ago (though others may emerge, and Fallon refers to “false” allegations in recent days.)
The second is that at present, one thing that is keeping the Conservative Party relatively calm was the prospect of a reshuffle that might refresh the top table. (That’s also keeping rebellious behaviour in check as no one wants to sabotage their chances of promotion.) Even a limited reshuffle – elevating, say, a junior defence minister and bringing in one fresh face at the Ministry of Defence – may leave bruised egos that cannot be easily soothed.