The only other option is for the Independent group to precipitate a general election ......

I would have thought a GE is the last thing many of the defectors would want. Some (many?) are likely to lose their seats; in the two party, FPTP system, the electorate vote for parties, not individuals, however effective they have been in the past as MPs, and however eloquent and principaled their stance.

The party leaders have already challenged the defectors to put their decision to "a people's vote" by resigning their seat and forcing a by-election. Noone has accepted this.

BBC Vox-Pop interviews in Conservative constituencies and press comment, even in more left-wing press, suggest that Allen, Soubry and Wollaston are not being lauded for their decision to challenge the ERG from outside the party.

Unless the Tory party does split completely under the default "no-deal", the "three amigas" stance may be irrelevant within two weeks.