In a keynote speech at the annual party conference in Liverpool, the Labour leader expressed his ambition for two terms in government to heal "13 years of Tory wounds" through a "decade of national renewal".

In a pitch to blue-wall voters, Sir Keir said the government's mindset is to "exploit problems not solve them".

Politics Live: Group claims responsibility for Starmer glitter protest

He added: "So if you are a Conservative voter who despairs of this, if you look in horror at the descent of your party into the murky waters of populism and stability, with no argument for economic change.

"If you feel that our country needs a party that conserves, that fights for our union, our environment, the rule of law, family life, the careful bond between this generation and next.

"Then let me tell you: Britain already has one. And you can join it. It's called the Labour Party."

The hour-long speech was not policy-heavy but set out the defining values of a government led by Sir Keir if he wins the next election.

Beth Rigby analysis: Aides' relief as Starmer delivers 'speech of his life'

With a theme of "getting Britain building again" recurring throughout, Sir Keir repeated promises for 1.5 million new homes, new towns, modernised infrastructure and support for green industries.

The plans, trailed by Labour earlier this morning, involve "bulldozing" planning restrictions and giving state-backed companies powers to acquire land cheaply in order to create new suburbs with amenities such as GPs and transport links "hardwired" into them.

It replicates the policy of Clement Attlee's post-war government which built 10 new towns during the 1950s, with Sir Keir saying that "sometimes the old Labour ideas are right for new times".

Click to subscribe to the Sky News Daily wherever you get your podcasts

In a nod to what could be a key battleground issue at the next election, Sir Keir said the plans don't mean "tearing up the greenbelt" but where that protection was "clearly ridiculous" - like disused car parks - "then this can't be justified as a reason to hold our future back".

Repeating the argument made by shadow chancellor Rachel Reeves yesterday, he stressed the need for "iron discipline" with the public finances, but insisted that planning reforms will help grow the economy by creating jobs and attracting investment.

Elsewhere in the speech, the Labour leader set out the importance of helping people with the cost of living squeeze and reforming the NHS from a "sickness service" to one which focused on preventing illness.

Read More:
Who is Starmer's wife?
From Starmer's glitter to Thatcher's vow: Stand-out conference moments

He has previously promised to end non-dom tax status to funnel money into the health service and said Labour would "guarantee" mental health treatment, end the "8am scramble" for a GP appointment and consign "dangerous waits" for cancer treatment to history.

Despite his party enjoying consistent double-digit poll leads over the Tories, Sir Keir has acknowledged there is still work to do to win over voters and has been using the conference, likely the last before the next election, to give people a reason to back him other than being fed up with the current incumbents of Downing Street.

Sir Keir said in his speech he was seeking "to answer the question 'why Labour?' with a plan for a Britain built to last".

Speech 'really sparkled'

The speech was briefly disrupted by a protester who stormed the stage and threw glitter over the Labour leader - but Sir Keir brushed the incident off by insisting it showed why he had changed his party from one of protest to one ready for power - in a dig at former leader Jeremy Corbyn.

Fans of the speech also sought to make light of the issue with Gavin Sibthorpe, a GMB union political officer chairing the next session, who said: "Conference, wasn't Keir brilliant? He made a speech which really sparkled."

However, while lots of union figures praised Sir Keir, Sharon Graham, general secretary of Unite, repeated her calls for him to be bolder with "big ticket" policies such as nationalising energy.