5.00 - I'm going to call it a night (morning) and head back to London. Thanks for sticking with me this long. My colleague Alex Stevenson will be picking up on all the fallout from tonight's result as the rest of the country wakes up...
4.30 - Mark Reckless has won with an almost 3000 majority and around a 7% lead. This is at the lower ends of Ukip's expectations but it is still a crushing defeat against the Tories who just weeks ago were predicting that they would retain this seat.
Here's what it means for the five main parties:
This is a massive victory in a seat which has never been ideal territory for Ukip. If Nigel Farage's party can win by-elections in places like Rochester, then they can expect to pick up far more favourable seats at the general election as well. This by-election also heralds the end of Ukip's amateurish reputation. Mark Reckless won today despite massive spending from the Tories and intensive campaigning from the grassroots all the way up to the prime minister himself.
David Cameron confidently predicted the Tories would hold on in Rochester. He personally visited the seat five times and ordered all of his MPs to visit at least three times. Cameron staked the house on holding onto Rochester and ended up losing the bet. They will now try to shift the focus back onto Labour, but while Ukip have cost Labour votes they are costing Ukip seats. Reckless' defection and subsequent victory is also likely to cause further defections from the Tories but even if it doesn't, it will certainly make voters feel that a vote for Nigel Farage's party is no longer a wasted one. It is those defections of votes, rather than the further defection of MPs that could really damage the Tories.
Ed Miliband will also face questions today over his party's poor showing in a seat which (slight boundary changes aside) his party once held. He will likely respond that this was a two horse race and that Labour were always going to be squeezed. This is perfectly true, but Labour's refusal to properly fight this seat has made them look both weak and cynical. Neither is a good look for a party that is hoping to form a government in just a few months time.
This was a fairly good result for the Greens. Environmental issues are quite prominent in the Rochester area with controversy over a local bird sanctuary and Boris Johnson's estuary airport both big issues with voters. Their strong showing tonight may be related to these issues but it is more likely a sign of the recent surge for the party nationally.
The Lib Dems were always going to get squeezed in this seat, but Nick Clegg's party were squeezed almost to non-existence. Clegg did not even bother to visist the area during this campaign and ordinarily he would expect to face heavy criticism for this. However, the Lib Dems have suffered a long series of dreadful results and lost deposits. If none of those stirred his party to rise against him, then this by-election won't either.
4.15 - Mark Reckless wins the Rochester and Strood by-election and becomes Ukip's second MP.
Ukip: 16,867 (42%)
Conservatives: 13,947 (35%)
Labour: 6,713 (17%)
Greens: 1,692 (4%)
Lib Dems: 349 (1%)
4.00 - The result appears to be fairly imminent. Lots of Ukippers, including Nigel Farage on the floor here. Very few Tories to be seen anywhere.
3.20 - Results for the Peninsula ward by-election are about to be announced. This ward was all solidly Conservative at the last local council elections.
Here they are:
Ukip 2850 (48%)
Con: 1965 (33%)
Labour: 716 (12%)
Green 314 (5%)
LD: 60. (1%)
That result isn't a million miles off the straw poll of the wider count we posted earlier.
2.44 - Lots of expectation management going on here at the count. The Tories are spinning that the result will be even worse for them than they really expect and Ukip are spinning that their majority will be significantly smaller than they really expect. Labour and the Lib Dems meanwhile are just hoping that nobody will notice quite how badly they do.
From sniffing around, it looks like the real result will be somewhere in the middle - a significant win for Ukip but not an overwhelming landslide. The truth is that spinners aside, most people don't care about what size the majority is. When it comes to by-elections, a win is a win and a loss is most definitely a loss.
2.00 - Enter Santa.
It's not just about the presents. He's got a political agenda as well.
1.40 - The Monster Raving Loony party are handing out free bananas. This is the higlight of the evening so far.
1.35 - Mark Reckless has just arrived at the count.
1.00 - Former Lib Dem MP Lembit Opik is on BBC Radio Kent alongside our editor Ian Dunt. Lembik has been incredibly complimentary about Ukip in general and Nigel Farage in particular. He has just revealed on air that he recently had dinner with Farage who he describes as "a natural leader". Could Ukip be about to get its first Lib Dem defection?
00.50 -The returning officer has just announced a turnout of 51%.
That's just about a majority of the electorate but only just. Even so, it's a relatively high turnout compared to some other recent by-elections.
00.30 - Mark Reckless has just received his first endorsement from a rival candidate. Britain First candidate Jayda Fransen has been speaking to reporters in the count room. "If Ukip win, Britain First policies win," she says. "There is very little difference between Ukip and Britain First." Unusually for a rival candidate, she goes on to say that she "sincerely hopes" Mark Reckless wins.
23.50 - The Kent Messenger have released a very unscientific 'exit poll'. It's not an official exit poll. There won't be any of those. Proper exit polls are massively expensive to produce and nobody is going to spend that kind of money just to find out a by-election result several hours before everyone else. However, it is the closest to one we're going to get. The Messenger spoke to 100 voters leaving polling booths during the day. Here's what they found.
Ukip – 49%
Conservative – 29%
Labour – 16%
Greens – 6%
Liberal Democrats – 0%
If the final result is anything like that, it will be a massive night for Ukip and an extremely worrying one for David Cameron.
23.30 - Emily Thornberry's resignation has thrown Labour into huge difficulties just as they were counting on all eyes being on turmoil in the Conservative party. The Labour party has developed a marvellous talent for turning almost every opportunity into a crisis.
It's not clear to what extent Thornberry's departure was a personal decision or under direction from the leadership. If it's the former then it seems like a massive over-reaction. If it's the latter then it's a massive miscalculation. All eyes will now be on Labour when they would otherwise have all been on the Tories.
Labour source update: "Ed and Emily had a second conversation. She thought the right thing to do was to resign. Ed agreed."— Paul Waugh (@paulwaugh) November 20, 2014
Miliband refuses to back his very impressive candidate in a winnable by-election, then manages to make Labour the story anyway. Genius.— Ian Dunt (@IanDunt) November 20, 2014
22.30 - Breaking - Emily Thornberry has resigned from the Shadow Cabinet over this tweet. Yes that's right. She's resigned over a tweet of a house.
This seems like utter madness to me. It was clearly an unwise tweet, which could be read as a snobby jibe about working class people in Rochester. But resigning over it has made it a much, much bigger story than it otherwise would have been. This was a small story for the blogs and diary pages. Now it will be front page news.
And here's that front page.
Our editor Ian Dunt has just been talking about this story on BBC Radio Kent. He'll be on air until six in the morning, if you can believe it.
10.00 - The polling stations have all now closed in Rochester and Strood and I'm here at the count in Medway Park. I'm sat on one of the most uncomfortable seats known to mankind, but I've got the thrill of a local by-election count to keep me going through the night. We're not expecting the final result until at least 3.am so sit tight for a long night of comment, speculation and inching despair as we wait to find out whether Rochester and Strood has a new MP and whether that new MP is exactly the same person as the old MP.
Mark Reckless is widely predicted to win tonight. One large betting company has already paid out on the result with the others offering oh-so tempting odds of 1/100 on a victory for Reckless. For novice punters, that means you'll win a grand total of £1 if you place a bet of £100 on the Ukip candidate. Don't all rush at once.
So let's start the evening off with a list of four things we've learnt from the Rochester and Strood by-election campaign.
1. Lynton Crosby is not earning his keep.
When Mark Reckless announced that he would be defecting to Ukip, the Tories confidently predicted that they would (in David Cameron's words) kick Mark Reckless' fat arse. Rochester was, we were told, going to be the line in the sand where Nigel Farage's forces were finally fought back. With it's relatively comfortable, youthful and metropolitan population, Crosby calculated that Rochester was not ideal Ukip territory. If the Tories could defeat a by-election challenge from Ukip anywhere then it would be here. Things just haven't worked out that way.
2. Ukip are now the natural party of protest.
Once upon a time, the Lib Dems were a by-election winning machine, hoovering up loose seats in all areas of the country. Their role in coalition has now killed that off potentially forever. Ukip were long thought to be too divisive to take their place with some predicting that they would suffer heavily from anti-Ukip tactical voting. This hasn't been the case in Rochester. In fact polls conducted during the campaign suggest that the party have actually benefited from tactical voters judging that Ukip are the best chance of giving the government (in David Cameron's words) a kick up the fat arse.
3. Anti-immigration sentiment now dominates British politics.
Immigration is not a big issue in Rochester and Strood, in the same way that it was in Clacton. But despite this Ukip, the Tories and Labour have spent this campaign all fighting over which party is to be seen as best placed to keep more foreigners from entering the country. This battle reached a new low after Mark Reckless suggested that some already settled migrants could be booted out of the country. This is the politics of the far right and Reckless' comments have already earned him the support of fascist group Britain First, who are also at the count tonight.
4. The two 'major' parties are in big trouble.
Tonight's result is set to be a terrible one for the Tories but it won't be much better for Labour. Their narrow win against Ukip in Heywood and Middleton and their predicted very poor showing tonight suggests that they are also losing lots of votes to Nigel Farage's party. Labour and the Tories are both hovering around the 30% mark in the polls, partly because of the rise of Ukip. A further boost for the party casued by tonight's result could end up depressing those dismal vote shares even further.