Labour will only return to power if it responds to the concerns of middle Britain, shadow justice secretary Jack Straw warned today.
Urging delegates to learn the lessons of the past, Mr Straw used his last major conference speech to say the party cannot succeed with only the support of the "weakest in society".
Instead Labour must appeal to people "who feel more secure about their incomes and their place", he said, insisting this is not "selling out".
But Mr Straw also hit out at "private extravagance" as he attacked the Government, and said the coalition's policies on crime and civil liberties risk making life easier for criminals.
"As Ed Miliband has said, the crucial thing is that we listen and stay connected to maintain the confidence of the vast majority of the British people," said Mr Straw, who is stepping back from frontline politics after 30 years on Labour's front bench.
"This is not about selling out, or any of that nonsense. It's about listening, listening carefully, and putting our timeless values into ways which protect and benefit people as their lives - and their circumstances - change."
Mr Straw repeated calls from new leader Mr Miliband to appeal to the "squeezed middle".
He said: "We mould our own future. If we are to stay relevant and electable in 2015 we have to learn the lessons of our past.
"It took years of work by Neil Kinnock, John Smith, Tony Blair and Gordon Brown, to undo the damage of the 1980s and reconnect us with all the people for whom this party works, recognising a fundamental truth: that we can only help the poorest and most insecure if we are in government.
"And we can only achieve government by building our support not only amongst the weakest in society but crucially among, as Ed has said, the squeezed middle and amongst those who feel more secure about their incomes and their place."
Mr Straw said the coalition agreement drawn up between the Conservatives and Liberal Democrats represented the "worst of both parties" as he issued a stark warning about Government policies.
"Conference, our great legacy on equal rights and public safety is at risk," Mr Straw said.
"The Liberal Democrats have conspired to put the Human Rights Act under review. The Conservatives, meanwhile, are going to cut the use of DNA technology and CCTV, and restrict the ability of the police and local communities to fight the scourge of anti-social behaviour.
"And who will benefit from this madness? There'll be greater freedom for the criminal, less liberty for the law abiding. It's crazy."
Seeking to set out dividing lines between Labour and the coalition, he added: "Equality is the most important idea which separates us from the Conservatives and the Liberal Democrats.
"We know that the countries which are healthiest, happiest and most secure are also those which offer the most equal societies.
"Equality is not uniformity. It's not about making everything and everyone the same. It is certainly not about levelling down. It's about recognising and celebrating that every individual is different, and entitled to an equality of rights, of dignity, of the opportunity to realise their dreams to the greatest extent.
"And equality too is about opposing private extravagance and public squalor."
Mr Straw was given lengthy standing ovations both before and after his speech.
Shadow home secretary Alan Johnson used his own speech to make fun of Mr Straw before his valedictory appearance.
He said: "This is Jack's last conference as a frontbench representative of our party and frankly I've had enough of these jokes about the length of time Jack has been around.
"I know I said last year I was grateful to him for having helped Keir Hardie set up the Labour Representation Committee but I think there's been enough of that, frankly.
"His experience has been of enormous value to the party. For example, when Clause Four was redrafted, it was really helpful that Jack had worked with Sidney and Beatrice Webb on the original version.
"We on the shadow cabinet - Jack, this is a surprise, Harriet (Harman) knows this - we've clubbed together to buy you a farewell gift. It's an express chairlift - it gets you upstairs before you've forgotten what you went up there for."
Mr Straw then started his speech with a dig at Mr Johnson.
"People often ask me why, as somebody so fit and fresh, I've decided to go to the backbenches," he said.
"Well, I'd better tell the truth now - it's the constant harassment by Alan Johnson, who I thought was a friend, about my age.
"Alan's a man who thinks the secret of eternal youth is to remind himself every minute of the day that he's younger than me.
"And that's true - I was born on August 3 1946 but, guess what - Alan was born on May 17 1950. He has in his pocket a bus pass for the elderly just like me."
Mr Straw said he was happy that "despite the scale of our defeat in May, we have begun our fight back in such a united manner".
He told party members: "Now that Ed has become our leader, we should all back him in the difficult task of developing our response to the Government's cuts agenda and the social and economic damage which they will cause.
"But beware that as the cuts begin to bite, and distress and anger about them rises, so too will the tendency of some people on the left to divide."
Mr Straw urged Labour activists to "challenge the myths of Labour in power now being peddled by the Conservatives and Mr Clegg".
He said: "We did build more schools and hospitals; we did recruit more teachers, nurses, doctors and police officers. And the results were improved outcomes for everybody."
To loud applause, he concluded: "With the unity this conference is demonstrating, the effectiveness we've seen of our party in Parliament and in the country, and with the development of new policies for new times, we do have the strength and the energy to work relentlessly over the next four-and-a-half years for that imperative for our nation - a Labour victory in 2015."