You're peddling the typical ERG and hard brexshit fib by conflating that which the manifesto (I assume you meant the Conservative manifesto) set out
in 2017 with Vote Leave's claims during the referendum -
in 2016, THE YEAR BEFORE. During the referendum it was all about leaving, with no clear vision of how that would actually happen, except that the EU needed us (apparently) more than we needed them and so a DEAL - would be simples. But, remember the hapless faces of Boris and Gove, when the were interviewed together on TV the day after the result. Clueless. Gove subsequently supported May's deal; which was designed to avoid a no-deal catastrophe. Boris slithered off to focus on his next bout of adultery having again broken another marriage solemn promise to his second wife having already broken his marriage promise to his first - serial lies come so naturally to this bloke and how much easier when its to the wider British public - whatever fits his bloated selfish sense of entitlement.
So, no-deal doesn't have a mandate unless your claiming that every person who voted Tory in 2017, must have agreed with no-deal, which is ludicrously simple-minded.
Even during the referendum, Vote Leave said precious little that was intelligible except resorting to blaming others (foreigners in the uk, the EU politicians, etc.)for all of their woes and making false promises to the ever-gullible and pertetually disgruntled, sector of the electorate, whose motivation for voting Leave were various and complex. The only touted positive made by Leave were false claims that leaving would be straightforward and we'd all be winners soaking up the largesse. Indeed, Vote Leave then subsequently and sneakily retracted much of what they promised just after he results came out!
https://www.independent.co.uk/news/u...-a7105546.html
What amuses me is how many Leavers, after disparaging experts prior to the referendum vote, suddenly become their own purveyors of expertise on what everyone else who voted Leave clearly understood and wanted. Strangely, the opinion seems to be that what they - the Leaver voters - wanted, always seems to accord exactly with whatever the particular Leave 'expert' believes him or herself :) You couldn't make it up - oh hang on, they did!