It occurred as a provision of the Conservative–Liberal Democrat coalition agreement drawn up in 2010 (after a general election that had resulted in the first hung parliament since February 1974) and also indirectly in the aftermath of the 2009 expenses scandal.

[16] At the next general election in 2001, Labour's manifesto stated that the party would review the experience of the new systems (in Scotland, Wales and Northern Ireland) and the Jenkins report, to assess the possibility of changes to the Commons, which would still be subject to a referendum.

[17] Electoral reform in the Commons remained at a standstill, although in the Scottish Parliament, a coalition of Labour and the Liberal Democrats introduced STV for local elections in Scotland.

Honouring a pre-election pledge, the Liberal Democrat leader Nick Clegg entered into negotiations with the Conservatives as the party who had won most votes and most seats.

According to The Guardian, reporting after the Queen's Speech, unnamed pro-referendum Cabinet members were believed to want the referendum held on 5 May 2011, to coincide with elections to the Scottish parliament, the Welsh assembly and many English local councils.

Nick Clegg's prior hope of a referendum as early as October 2010 was considered unrealistic due to the parliamentary programme announced in the speech.

[28] The plans to hold the vote on 5 May faced criticism from some Conservative MPs as distorting the result because turnout was predicted to be higher in those places where local elections were also held.

In Wales, the question on the ballot paper also appeared in Welsh: Ar hyn o bryd, mae'r DU yn defnyddio'r system "y cyntaf i’r felin" i ethol ASau i Dŷ'r Cyffredin.

"[58] The UK Independence Party's National Executive Committee formally announced that it would be supporting Alternative Vote, although it would prefer a proportional system.

[80] Also supporting the "Yes" campaign were over 50 Labour MPs including Alan Johnson, Peter Hain, Hilary Benn, John Denham, Liam Byrne, Sadiq Khan, Tessa Jowell, Ben Bradshaw, Douglas Alexander,[81] Alistair Darling,[82] Diane Abbott and Debbie Abrahams.

[90] Over five Labour MPs announced as opposing AV were also found to have been wrongly included:[91][92] for example, Alun Michael supported a "Yes" vote,[91] while Meg Hillier did not lend her name to either campaign.

[97] Take Back Parliament,[98] the Electoral Reform Society,[99] Make My Vote Count,[100] and Unlock Democracy[101] all campaigned in favour of the change to AV.

[118] On 11 March 29 historians, including Niall Ferguson, Simon Sebag Montefiore, Andrew Roberts and David Starkey, wrote to the Times expressing opposition to the adoption of the Alternative Vote.

[134] Supporting a "No" vote were television presenter Esther Rantzen,[135] scientist and Labour peer Lord Winston;[75][136] nightclub impresario Peter Stringfellow, cricketers David Gower and Darren Gough, Olympic rower James Cracknell and F1 boss Sir Frank Williams.

[75] A group of leading businesswomen and campaigners published a letter in The Guardian backing a "Yes" vote on 28 April 2011, with signatories including Alexandra Shulman (editor of Vogue), illustrator Daisy de Villeneuve, writer Gillian Slovo, human rights lawyer Helena Kennedy, Hilary Wainwright (editor of Red Pepper), journalist Isabel Hilton, Jacqueline Rose, writer Jay Griffiths, broadcaster Joan Bakewell, rabbi Julia Neuberger, fashion designer Patsy Puttnam, journalist Polly Toynbee, Janet Todd (President of Lucy Cavendish College, Cambridge), Chair of Young Labour Susan Nash, activist Tamsin Omond, financial consultant Tessa Tennant, fashion designer Vivienne Westwood, gynaecologist/campaigner Wendy Savage and journalist Yasmin Alibhai-Brown.

The "Yes" campaign also received five-figure sums from Alan Parker, who is close to both Gordon Brown and David Cameron, and Paul Marshall, a donor to the Liberal Democrats.

[145] In total, the "No" campaign had raised by that date £1.8m in donations of over the declarable limit of £7,500 from 41 donors, with the largest being from billionaire Peter Cruddas, founder of the CMC spread betting firm, who gave £400,000.

Clegg argued that AV would mean "fairer votes" and that FPTP produced more safe seats, and linked these to the MPs' expenses scandal.

[150] Caroline Lucas, head of the Green Party of England and Wales said in support of AV that "they can vote for what they believe in and I think that will be very liberating for a lot of people".

[38] A Channel 4 News Fact Check concluded that the specific claim that AV would require electronic counting machines, the main component of the £250 million figure, was "fiction".

He also told the Independent on Sunday newspaper: "I don't expect to see any increase in the cost of holding a general election if the British people vote yes.

The report of the Independent Commission on the Voting System, issued in 1998, stated that "There is not the slightest reason to think that AV would reduce the stability of government; it might indeed lead to larger parliamentary majorities.

"[165] During the referendum campaign a BBC Newsnight special on the referendum suggested that AV would lead to a small increase in the number of hung results[38] and Alan Renwick, author of A Citizen's Guide To Electoral Reform, wrote in Total Politics magazine that "AV makes election results more volatile, exaggerating landslides on the one hand and making coalitions more common on the other.

Rawlings and Thrasher stated that "the claims that AV will guarantee local majority support can only be validated if every voter is compelled or chooses to cast a full range of preferences.

[183] On the other hand, Thomas Lundberg, an electoral systems specialist at Glasgow University, wrote in a Political Studies Association paper: "Anything that reduces the ability of small parties to win seats – a process that has been going on since the 1970s at British general elections – could be detrimental to the prospect of a PR transition.

In response, Conservative chairman and "No" supporter Baroness Warsi described AV as "a system which rewards extremism and gives oxygen to extremist groups".

"[190] Dennis Leech, a professor at Warwick University, has argued that extremists like the BNP are more likely to win under FPTP, but he has also argued against the notion that AV automatically favours centrists: while AV prevents the kind of undemocratic result that often occurs under FPTP, and always ensures that the winning candidate has at least some kind of majority support, it has nothing to do with proportional representation.

The "No" campaign countered, quoting a senior returning officer (Anthony Mayer), who said that voting machines would be essential with AV if results are desired as quickly as today, rather than counting over the weekend after a general election.

Hodges also reported that an aide of David Cameron secretly met "No" campaign leaders in a hotel room in order to stop the Liberal Democrats finding out the scale of Conservative involvement.

"[208] Tim Ivorson of the electoral reform campaign group Make Votes Matter responded by quoting the petition's text that "The UK has never had a say on PR.