The successful campaign to keep the first-past-the-post system for choosing MPs outspent supporters of electoral reform by more than £1.25m, official figures published yesterday show.
The Electoral Commission disclosed that the groups which argued for a No vote in the referendum in May accumulated a war-chest of £3,472,213. By contrast, advocates of a switch to the Alternative Vote spent £2,209,748 getting their message across.
The disparity of £1,262,465 is unlikely to have made a difference to the outcome of the referendum, in which voters rejected a move to AV by a majority of more than two to one.
But it underlines the financial firepower that the No campaigners were able to unleash in the run-up to the vote.
They were for instance able to fund two national mailshots, while the Yes campaign only had enough cash to target selected addresses.
The No team could also afford national poster campaigns, including controversial images claiming that the money used to move to AV would be better used to save babies' or soldiers' lives.
Most of the money used to oppose the change went through the official No campaign which poured £2,598,194 into its publicity effort. The Conservative Party contributed a further £660,787, while the Labour No to AV campaign spent £192,084.
On the other side of the battle, the Yes in May 2011 organisation spent £2,139,741. The Liberal Democrats only found £62,782 despite viewing securing the referendum as a key victory in negotiations over the terms of the Coalition Government.
Although Ed Miliband was in favour of AV, Labour Yes was unable to stump up any money. The No campaign was supported by 200 Labour MPs, but much of the financial and organisational muscle was provided by Tories.
The Conservative peers Baron Sainsbury of Preston Candover, Lord Harris of Peckham and Lord Fink, the Tory treasurer, all donated substantial sums.
At the turn of the year, polls suggested the Yes campaign was on course for a comfortable victory. At that point David Cameron, who was warned his leadership could be in peril if the referendum backed AV, became heavily involved and the weight of the Tory machine swung behind the No campaign.
It used aggressive tactics to turn round the polls, its hard-hitting publicity eclipsing its opponents who were determined to run a grassroots-style campaign.
In the end the No campaign scored a triumphant victory as Britain rejected AV by 67.9 per cent to 32.1 per cent. Just 10 out of the 440 counting areas voted for electoral reform.
A former activist in the Yes camp said they were always fighting an uphill battle given Nick Clegg's unpopularity during the campaign and Labour's split on the issue. But he added: "The other side had the money to rip up things and start again when it didn't look good for them. We didn't have that luxury and had to continue on our set course."