Just last month shadow home secretary Diane Abbott called for free movement of people should be defended as a workers' right, in the foreword to a book. We will work with trade unions, businesses and stakeholders to ensure there is a consensus on this vital issue.
He said: "Only Labour or the Tories can form a government, and I implore Scots to fight for the party of progress, and not the vicious Tory Party, who, alongside their previous coalition partners, the Lib Dems, unleashed an unprecedented attack on working people in this country".
One audience member said Starmer's speech made it clear that the best option for the United Kingdom was to remain an effective member of the European Union and asked why Labour was not simply nominally leaving the European Union but remaining an effective member.
Starmer said that a Labour government would rewrite May's Brexit negotiating strategy and would focus instead on a deal that retained as numerous benefits as possible of the single market and customs union.
Labour councillors Ansar Ali and Ed Murphy have both said they have put their names forward to represent the party in Peterborough in June's election, with a decision expected to be made either this week or next.
Mr Starmer said the United Kingdom should be willing to forego striking its own trade deals with other countries in order to secure the best possible trading access with the EU.
Starmer rejected claims the Tories have a "clear" approach to Brexit and said they only offered a "rigid approach, a reckless approach".
French election result gives markets a start-of-week lift
Protesters burned cars, danced around bonfires and dodged riot police overnight at the Place de la Bastille and Republique. National Front vice president Steeve Brios said: "The voters who voted for Mr Melenchon are angry voters".
That gives her the freedom to focus on Brexit and a handful of other measures which she might otherwise have struggled to get past even her own party, such as new selective grammar schools, or those which are less traditionally associated with the Conservatives' laissez-faire economic policy.
He was referring to the Tories' approach of leaving all EU-related agencies, which he described as contrary to any sensible negotiation - when each side seeks to keep their options open.
Mr Starmer told BBC radio Mrs May's stance was part of her "rigid" and "reckless " strategy that was alienating European Union negotiators before the talks have started in earnest and that Labour would set a more conciliatory tone to win a good deal which would include preferential access to the bloc's single market.
Under Labour's Brexit strategy, the Great Repeal Bill would be replaced by an EU Rights and Protections Bill.
Responding to Sir Keir's remarks, Brexit Secretary David Davis said Labour's promise not to walk away from exit talks "really undermines" Britain's negotiating position. "He is an honest, caring politician and we have a real opportunity to change our society for the better".
"What we have seen today from Labour is I think their seventh Brexit plan".