British Environment Secretary delivered his first major speech to the WWF charity.
"Talks will show us whether he is sincere and bringing fresh thinking to the table," Cash said.
Theresa May's cabinet are reportedly behind the shift in tone after a week-long briefing war.
"We need to prepare for an exit from Brexit," the former business secretary said.
Ipsos MORI also shows that Labour leader Jeremy Corbyn has seen his satisfaction scores rise.
Brexit Secretary and EU's chief negotiator have failed to find a compromise on the issue.
Gina Miller beat Theresa May in the High Court and Supreme Court to give MPs a say.
Natalie Bennett speaks to IBTimes UK about the 2017 general election and her move up north.
Exclusive: Former Greek finance minister warns of European-wide incompetence.
EastEnders' Tameka Empson and BBC News' Moira Stewart are among those featured.
House of Lords' EU Select Committee issues warning to prime minister.
Nick Tyrone, the director-general of the group, speaks to IBTimes UK about EU regulations.
Employers are being urged to hire more ex-military staff in a bid to utilise their skills.
Jüri Ratast warned May that Brexit will impact on the everyday lives of many Europeans.
House of Commons Commission refuses to comment on email hack due to security concerns.
French president's business-friendly approach is winning him friends across the globe.
House of Lords' EU Home Affairs Committee issued warning to the Conservative government.
Canadian MPs saw their email accounts 'temporarily deactivated', authorities tell IBTimes UK.
Prime Minister Theresa May faces another Brexit-related headache as public mood shifts.
Dominic Grieve, Maria Miller and Dame Caroline Spelman have made circa 70 recommendations.
Michael Barnier and David Davis will also discuss a £87bn Brexit bill in Brussels.
"We do not have the tools necessary to investigate and prevent these attacks," Diane Abbott warned.
Theresa May has refused to sack the Labour peer as chair of the National Infrastructure Commission.
Interview: Rob Greig, the House of Commons' online guardian, speaks to IBTimes UK.
EU's chief Brexit negotiator also met with Welsh First Minister Carwyn Jones and SNP chief Nicola Sturgeon.
Conservative premier reflected on the general election and her 12 months in Downing Street.
Failure to get draft law through the Commons and Lords would see the end of Theresa May's premiership.
Peter Whittle and John Rees-Evans reach out to the party's grassroots after a 'terrible loss' in morale.
A look back at the Conservative premier's time in Number 10 shows where it went wrong for May.
Shadow foreign secretary tore into the UK government over Brexit as she stood in for Jeremy Corbyn.