Speaking about the tweet sent by the shadow attorney general - for which she later resigned from Labour's front bench - Mr Cameron said: "Emily Thornberry is one of Ed Miliband's closest allies and aides.

"Effectively what this means is that Ed Miliband's Labour Party sneers at people who work hard, who are patriotic and who love their country, and I think that is absolutely appalling."

Image source, PA

The prime minister has just been seen at Paddington station in central London, after his party lost the seat of Rochester and Strood.

Prime Minister David Cameron says of the Rochester and Strood result: "I am absolutely determined to win this seat back at the next general election because anything other than a Conservative government will put our recovery at risk and Ed Miliband in Downing Street. I am more determined than ever to deliver security for Britain."

Dave Poole tweets, external: Reckless has already been sworn in as #UKIP MP for #RochesterandStrood. This House of Commons is starting to take shape nicely!

The BBC's Robin Brant tweets this picture, external with the message: "Here's @Ladbrokes take on a 3rd defector."

Claire Mansfield in London tweets, external: Surely all #rochesterbyelection proves is don't underestimate the power of the personal vote.

There was some heckling from Labour MPs as Mark Reckless took the oath - but the Conservative benches were largely empty.

It is unusual to be sworn in on a Friday. The Commons ordinarily only takes backbench bills and often does not sit at all.

Steve Bedder emails: "I agree with Bry and the swing to UKIP is a protest vote which is not seen as a wasted vote. Looking ahead, if there was a box on the General Election ballot paper marked "none of the above" then would there be a swing from UKIP to this protest vote?"

Image source, Douglas Carswell

Mark Reckless's fellow UKIP MP Douglas Carswell tweeted, external a photo of the pair, with the message: "Selfie selfie! Woohoo!".

Mark Reckless said after being voted back as MP for Rochester and Strood - albeit for a different party - how he "thought [going] straight back to work was the best thing".

Prime Minister David Cameron says he is "absolutely determined to win" the Rochester and Strood seat back for the Conservative party, following Mark Reckless's victory there for UKIP.

Mark Reckless is seen here being sworn back in as a Member of Parliament at Westminster, this time as a representative of UKIP.

Sarah Louise Stewart in Kent tweets, external: Oh no. Very disappointed but not overly shocked at the UKIP result in Rochester. Staying hopeful its just temporary #rochesterbyelection

Mark Reckless has been sworn in at Parliament. Douglas Carswell, the first Conservative defector to be elected for UKIP, and Conservative MP Philip Hollobone escorted Mr Reckless into the chamber at the Houses of Parliament.

Steve Buc emails: "The common argument against UKIP is that they don't have any policies. They do however, have principles and will deliver those. The other parties do have those treasured policies, but don't deliver on them in any case. So the argument about policies is weak."

BBC Radio 5 live wants your views, and has tweeted, external details of how to get in touch: "Your Call: UKIP has won its second by-election. Is #UKIP for you? Call 0500 909 693."

Matthew Harrison in Manchester tweets, external: #UKIP have won two seats without the MP changing. Odd to claim victory over anyone other than the #Tories. #RochesterandStrood

Image source, Mark Reckless

Mark Reckless has tweeted, external this picture of himself outside the Houses of Parliament, with the message: "With my Certificate of Return to swear in at 9.30am. Thanks to @vincemaple and Medway Labour for arranging."

You can watch a report on UKIP's win in Rochester by the BBC's political correspondent, Chris Mason, here.

Graeme emails: The main political parties still don't get it -we are sick of "career" politicians telling us what's best for us and of Europe's total lack of democracy-watch this space people like upsetting "them" and that is what is going to happen!