Woman leaves £500,000 to coalition parties
A woman who left more than £500,000 in her will to the Tories and Liberal Democrats specified the money should go to "whoever is in government".
The Conservatives received £420,576 from Joan Edwards' bequest during the second quarter of this year, while the Lib Dems got £99,423.
The Lib Dems said the money had been shared according to the number of MPs and ministers of each coalition party.
Ms Edwards was the biggest donor to both parties between April and June.
There are no further details about her at this stage, although she is not thought to have had any involvement in politics.
'Out of the blue'
A Conservative spokesman said: "We don't comment on the details of specific donations."
But he added: "It was out of the blue. We weren't expecting it."
Overall, the Conservatives returned to the top of the political funding table, receiving £4.12m donations in the three months to June.
Labour, given the most money in the previous quarter, received the second largest amount - £3.14m.
Unite, Britain's biggest trade union, gave £772,000 to Labour, the single largest amount from any person or organisation to any party.
During the previous quarter, multimillionaire John Mills was Labour's biggest donor.
Labour leader Ed Miliband has pledged fundamental reform of the unions' relationship with the party after the controversy over Unite's involvement in candidate selection in Falkirk.
But the figures underline the continued importance of union money to the party.
In addition to the Unite donation, the GMB union gave Labour £486,830 from April to July, Unison contributed £458,000 and Usdaw £411,000.
Meanwhile, the Conservatives' largest donors after Ms Edwards were party treasurers Michael Farmer, a City financier, and James Lupton, a former director of Barings bank, who gave £281,000 and £263,000 respectively.
The National Conservative Draws Society, which runs weekly prize draws, gave £165,000.
Offshore Group Newcastle donated £117,000 to the Conservatives. This year, the company launched the first complete North Sea oil platform built in one British yard for 25 years.
For Labour, shadow justice secretary Sadiq Khan said: "Hardworking families are seeing their living standards squeezed, with prices rising faster than wages. Meanwhile David Cameron shows how out of touch he is, standing up for the millionaires who fund his party."
But Conservative chairman Grant Shapps said: "Despite Ed Miliband's promise of change, these independent figures prove his Labour Party is still dominated by the trade unions. They choose the candidates, pick the leader and remain Labour's biggest donors - providing three quarters of the party's money."
The third-placed Liberal Democrats received £801,000 in total, with Ms Edwards their biggest single funder.
Fourth in the donations table was the UK Independence Party, on £153,229 - double the amount of the previous quarter.
The British National Party received £98,000 and Plaid Cymru £82,000.
In the previous quarter, Labour was the best-funded party, receiving £3.68m, including £1.65m from John Mills, an entrepreneur who founded the television shopping channel JML.
It narrowly beat the Conservatives, who were given £3.66m.