A brief guide to election night
The hardest thing on any election night is judging who won and who lost. What's more you have to decide whether that matters.
The answer is that tonight's results do matter.
Of course these are not elections for the government.
Of course, not everybody has a vote.
Of course, opposition parties can do well on nights like this and still not get back into government.
However, it is not just political commentators who will look to tonight's results as a guide to the state of politics just under a year after Gordon Brown became prime minister.
The spin doctors will, of course, pick which ever figure helped to make their case. I will be looking at a number of different tests:
• National vote share - not the actual votes cast but a calculation of what share of the vote each party would have got if this had been a national election - the boffins call it the projected national share or PNS
• Councillors gained and lost
• Who wins London
Tonight cannot help but be a difficult night for Labour. The question is - how difficult? If Ken Livingstone holds on, if the party is not pushed into third place and if its vote share is above 26% (the lowest figure that Tony Blair got) expect Team Brown to look very relieved.
Tonight should be a good night for the Tories. The question is - will it be good enough? If Boris Johnson wins, if their vote share is comfortably above the 40% they've gained in the past two years and if they gain 200 or more new councillors they'll be well pleased whilst being well aware that Tony Blair did much better than that before he won his landslide victory in 1997.
Tonight could be a tricky night for the Lib Dems. The seats up tonight were last fought in 2004 when the party's opposition to the Iraq war meant they were riding high. Nick Clegg needs evidence - a council gained here or there; beating Labour into second place, a vote share of 27% or more - to prove that he's moving his party forward after the fall of Ming.
The problem tonight is that we will only know part of that story. 2/3rds of council results will be declared but the rest come on Friday. London will not even start counting until the morning. The picture will emerge in the way a jigsaw does. Occasionally, people will disagree about what the parts add up to.
Stay with me through the night as - working from the BBC's election studios - I pass on the latest titbits of information and feel free to tell me what you've picked up too.