The Rochester and Strood by-election won't be as straightforward for UKIP as Clacton seems to be.
As Mark Reckless told the UKIP conference today, "Rochester is not Clacton".
It certainly didn't figure high up on UKIP's list of target seats - until about 3 o'clock this afternoon. And Mr Reckless probably doesn't have the same personal followng as Douglas Carswell.
But, in the Medway Council area as a whole, UKIP won the European elections, getting almost twice as many votes as the Tories. And voters there consistently say immigration is their top concern.
We don't know the date of the by-election yet, but it will come after the two taking place on October 9th. So UKIP will be able to put all their resources into Rochester and Strood.
If Mr Reckless does manage to overturn his own 10,000 majority, it will be another one of those political earthquakes Nigel Farage likes to talk about. And perhaps the most significant so far.
Phil Hornby ITV Political Correspondent
Mr Reckless announced that he will quit as an MP so he can trigger a by-election and fight the Kent seat as a Ukip candidate.
He told activists he answered to his constituents and wanted to seek their permission to change allegiance. "They are the boss and if I am to seek to represent them under different colours, I hope in a party that is closer to their values, then I shall ask their permission," he said.
"So I will resign my seat in Parliament, trigger a by-election and, your national executive allowing, stand for Ukip."
Conservative backbencher Mark Reckless said he is defecting to Ukip because he "found that it is impossible" to keep promises he gave to his voters as a Conservative.
"I remember the promises I made to my constituents in Rochester and Strood at the last election, and I intend to keep them," Mr Reckless said.
"I found that it's impossible to keep these promises as Conservative and that is why I am joining Ukip," he said.
The Rochester and Strood MP said he had not taken the decision lightly but claimed the Conservative leadership was "part of the problem that is holding our country back".
Conservative MP for Rochester and Strood Mark Reckless is joining Ukip, he announced today at the party's conference. "Today I am leaving the Conservative Party and joining Ukip," Mr Reckless said.
Mark Reckless, Tory MP for Rochester and Strood has denied being one of the Conservative MP's rumoured to be about to defect to UKIP. But he says he wants a referendum on Britain's future with Europe, and he would vote to leave the EU.
He is one of a growing number of Tory backbenchers who say they are increasingly fed up with the policy concessions being made by David Cameron just - so they say - to keep their coalition partners the Lib Dems happy.