For most of us, having an accident means losing our phone or spilling our drink. Jeremy Cliffe is cut from different cloth: he claims to have accidentally started a new political party. Being conceived by accident, however, does not in itself condemn one to failure - as millions of us can attest. What chance, then, does Radicals UK have?

Two things speak in its favour. One is that it will no doubt get lots of favourable media support from the many centrists who hate Corbyn. The other is that they are clean skins. The Lib Dems are discredited by the fact that they trebled tuition fees and collaborated with the economic illiteracy of austerity - which was of course a major cause of Brexit. Radicals UK will be untainted by such disgrace.

On the other hand, though, two more powerful forces are against it.

History warns us of these. Back in 1981 the SDP launched itself as a centrist party wanting to "break the mould" of British politics. The mould bent but didn't break. Within nine years, most of the SDP was subsumed into the Lib Dems, and the rest were beaten in a by-election by the Raving Loonies.

One reason why the mould didn't break is path dependency. Political parties are powerful brands that have been built up over decades. This loyalty doesn't only attract millions of voters. It means that members stick with the party through thick and thin, even if they profoundly disagree with their policies and leaders. This gives them a resilience that a new centrist party won't have. It also gives them an army of unpaid labour willing to deliver leaflets, get out the vote and speak up for the party in pubs and workplaces. Parties need bodies as well as heads.

Secondly, successful parties (unless perhaps they are nationalist ones) need some kind of class base and - given our electoral system - a geographically concentrated one at that. What would be the base of Radicals UK?

The party's promises to be pro-EU and comfortable with both immigration and new technology suggests the obvious base would be younger metropolitan types who voted Remain. Many of these, though, are Corbynistas - attracted to Labour by its (apparent?) offer to end austerity, tax the ultra-rich and solve the housing crisis. What can Radicals UK do to prise them away?

A few weeks back, Jeremy made some suggestions. Whilst many strike me as reasonable (such as shifting taxes from income to land and inheritances) only one speaks to Corbynistas' main concerns - the promise to build more houses. But I suspect that Labour could match that. Sure, it could mobilize discontent with Corbyn's lack of support for EU membership. But grudges fade whilst interests do not. Corbyn's huge appeal to the young declasse "middle-class" elements is founded on these interests. That gives Labour a class base that centrism will lack.

Yes, Radicals UK might appeal to less regressive elements of capital: firms wanting free migration and an open society. But there aren't many votes in this.

All of which suggests to me an analogy. We already have a political party comprising decent people with reasonable policies and which speaks for around half the country: the Women's Equality Party. And yet it is a nugatory electoral force. Why should Radicals UK be different?