Media playback is unsupported on your device Media caption Speaking on The World This Weekend, Lord Owen said that he would not rejoin the Labour Party

Co-founder and former leader of the SDP Lord Owen has given money to Labour, having hailed its "brave and bold" change to its links with the unions.

David Owen, a former Labour cabinet minister, made the announcement after the party backed Ed Miliband's reforms.

He said he had given up his status as a crossbench peer to give "over £7,500" but would remain an independent.

Labour leader Ed Miliband said he was "delighted" by the support but the Tories attacked Labour's union links.

Mr Miliband's proposals to change the link between the party and the unions were approved by an overwhelming majority at a conference of party members held in London.

'Desirable change'

Lord Owen quit the party in 1981 to set up the Social Democratic Party as one of the so-called "gang of four" with fellow Labour MPs Roy Jenkins, Bill Rodgers and Shirley Williams.

He said he hoped Labour would "rescue" the National Health Service, which would be "completely destroyed" without a change of government.

Media playback is unsupported on your device Media caption Labour leader Ed Miliband says he is delighted to have Lord Owen's support

He said: "This is a brave and bold reform by Ed Miliband and one I strenuously argued for as a Labour MP at the special conference on Saturday, 25 January 1981.

"This very desirable change, nevertheless, threatens to weaken Labour's financial support at a critical time when I and many others are hoping to see the party produce a plan for government from May of next year to rescue our NHS.

"Saving the NHS is my main political priority and I suspect that of many others. To help Labour reverse the 2012 NHS legislation without yet another major reorganisation, I have made a declarable contribution of over £7,500 to Labour funds. Unless there is a change of government the NHS in England will be completely destroyed by 2020."

The peer, who held positions in Labour governments including foreign secretary, added: "I want to support Labour but also value my independence. I have informed the convenor of the crossbenchers in the House of Lords of this.

"I will continue to sit, as allowed under their rules, on the crossbenches as I have done from 1992. However, since I can no longer be called a crossbencher under their rules, I will now be an independent Social Democrat."

Speaking on the World This Weekend, Lord Owen said he was "too old" to start taking the party whip after such a long time as an independent but he supported Labour and believed only it could deliver "substantive" changes to the NHS.

Mr Miliband said he had been speaking to Lord Owen for some time on a range of issues and the peer shared his concerns about the "fragmentation" of the NHS.

"I am very pleased to have David Owen's support. This is somebody who left the Labour Party 30 years ago because he was worried about its direction. I think it shows Labour reaching out...and winning people back to our cause."

Complete process

Mr Miliband had urged a "one member, one vote" system for leadership elections and an end to the automatic affiliation of union members.

He praised the party's "courage to change" after members backed the plans by 86.29% in favour.

The key changes A new method of electing Labour's leader - the electoral college, which gives unions, party members and MPs/MEPs a third of the votes each, abolished in favour of one member, one vote MPs have sole nomination rights for leadership candidates and those candidates will need a higher level of support than at present - possibly 15% of MPs All union members will have to 'double opt-in' if they want to take part in a leadership contest. They have to say that they are content to give money to Labour AND that they want to become 'an affiliated supporter' Only full party members - not trade union 'affiliated supporters' - will choose parliamentary and council candidates Changes to London mayoral selection - Labour's candidate to be selected in the same way as the party leader New leadership rules will be put in place this year - but changes to the party's funding will be phased in over five years

Mr Miliband said a "one-member, one-vote" system would complete a process started by former leader John Smith more than 30 years ago.

The proposals were prompted after Mr Miliband asked police to investigate the alleged rigging of a Labour candidate selection by the Unite union in Falkirk.

Unite leader Len McCluskey told the conference "my union has done nothing wrong" and declared: "This is our party and we are going nowhere."

Under the changes, unions would still control 50% of votes at Labour conferences, there would be no cap on union donations, and some of the changes would be phased in over five years.

Historically, millions of union members have been automatically affiliated with Labour, but few take part in campaigning activities or even vote in general elections.

Labour leadership elections have previously been decided by a complex electoral college system, with equal weight given to the votes of three groups - one third to MPs and MEPs, one third to ordinary party members and one third to trade unionists.

But the Conservatives said the changes were "a big victory for the unions, increasing their powerbase and ensuring they remain the dominant players in Labour politics for years to come".