As an expression of democratic principle it is unassailable.
Labour has "lost the right to call themselves the opposition" by failing to make a stand on Brexit, Mr Farron said.
The party believes there is no deal that could be as good as continuing European Union membership and would campaign to stay in, cancelling Brexit.
Farage is the former leader of the U.K. Independence Party and was one of the most prominent faces of the Leave campaign. Yet the expected wave of Europhilic support has not materialised, or, rather, it has not been sufficiently rallied.
Farron is also committing to lifting the public sector pay cap.
For Labour, shadow chancellor Mr McDonnell was on the road as Mr Corbyn took a day off campaigning following the launch of the manifesto, which had promised the renationalisation of key industries and huge increases in spending on public services, paid for by tax hikes on the rich and corporations.
While the Lib Dems have offered no specific mentions of which supports would be restored, solar and onshore wind could feasibly be allowed to compete in future Contracts for Difference auctions under the proposals, allowing the technology to be developed in "appropriate locations" as the manifesto suggests.
Banning diesel cars and helping young people buy their first home through rent payments are among other key policies. More important, it would release hard-pressed police officers to pursue more damaging criminally activities, of which there is no shortage.
The party says it will pump an extra £6 billion a year into health and social care through a 1p rise in income tax.
So why are the Lib Dems stuck on about 10 per cent in the polls, a little up on the last general election, but a very poor showing compared with their strength under previous leaders? They would increase the earnings threshold for income tax to £12,500 and the higher rate to £50,000 by 2020.
The Liberal Democrats nosedived in the 2015 election after five years as the junior coalition partner alongside the Conservatives.
Lib Dem policy chiefs said they estimated their model would generate revenues and savings at the higher end of the IESR range.
"The Liberal Democrats can not be trusted to stand up to the Tories - and as we know their manifesto pledges are not worth the paper they're written on". Unlike in the 2010 election, there will be no TV debate to trigger a Cleggmania-type phenomenon.
"As we have said time and time again the PRS needs effective enforcement, not more regulation".
Yet these explanations smack of excuses. In other words, to the Lib Dems, Brexit means Bremain.
The Liberal Democrat manifesto has committed to scrapping the freeze on benefits and injecting more than twice as much money into welfare as Labour. In 1983, with which this year is so often compared, the SDP-Liberal Alliance nearly beat Michael Foot's Labour Party in votes.
On the evidence of the Labour and Lib Dem manifestos, only one party answers that description.
Reflecting other Lib Dem obsessions, Mr Farron also pledges to legalise prostitution, challenge "gender stereotyping" in schools, pass laws to protect hens and bees, ban diesel vehicle sales and give the vote to schoolchildren of 16.