The successful campaign against changing the British electoral system outspent the rival 'Yes' campaign by more than a million pounds.
According to the Electoral Commission, the groups campaigning against ditching the first-past-the-post system combined spent £3,472,213, compared to the £2,209,748 spent campaigning in favour of the Alternative Vote.
In May 2011 voters overwhelmingly rejected proposals to change the voting system for Westminster elections by 67.9% to 32.1%.
Most of the money spent campaigning against the change was by the official 'The No Campaign Ltd' who funneled £2,598,194 into the effort.
The Conservative and Unionist Party contributed £660,785 and the 'No to AV, Yes to PR' group that opposed AV in favour of a proportional representation system spent £21,150.
On the 'Yes' side, the official 'Yes in May 2011 Ltd' organiastion spent £2,139,741. The Liberal Democrats, who secured the referendum as part of the deal that brought them into government, spent £62,782.
The Alliance Party of Northern Ireland donated £345 and and individual, Mr Alan Edward Rayner, spent £304.
The Conservative Party was opposed to the change, but a Conservative 'Yes' camp did spend £6,576.
The Labour Party was split on the issue despite Ed Miliband supporting the change. And while party's 'No' camp spent £192,084 opposing any change, the official Labour 'Yes' campaign spent £0.
According to the Electoral Commission the total amount of money spent was £5,681,962.