SNP welcomes Johnson as 'last Prime Minister of the UK'
SNP Westminster leader Ian Blackford was accused of 'defeatism and pessimism' by the new PM.
Boris Johnson has been welcomed to his post in the Commons as "the last Prime Minister of the United Kingdom".
SNP Westminster leader Ian Blackford made the claim as he urged the new Prime Minister to call an early general election, telling Johnson he has "no mandate" in Scotland.
Blackford accused the PM of living in "fantasy land" by thinking he can strike a new Brexit deal with Brussels - but Johnson dismissed his remarks as "defeatism and pessimism".
Johnson's first parliamentary appearance as Prime Minister will be the only such appearance until September, due to MPs rising for recess at the end of Thursday.
It comes as he held his first Cabinet meeting on Thursday morning, following a savage cull of former ministers and a raft of new appointments.
The departures included ex-Scottish secretary David Mundell, who has been replaced by Dumfries and Galloway MP Alister Jack.
Addressing MPs, Blackford hailed Johnson as the "last Prime Minister of the United Kingdom".
He added: "It's often said the Prime Minister lives in a parallel universe - that's been proven beyond any reasonable doubt this morning."
Blackford told him: "Scotland's First Minister has been clear that she is now reviewing the timetable for a second independence referendum.
"Scotland will not stand by and let decisions be taken by charlatans on our behalf."
The SNP Westminster leader added: "Do the honourable thing. Call a general election. Let the people of Scotland have their say.
Johnson replied: "The people of this country have voted in 2015, 2016, 2017 - what they want to see is this Parliament delivering on the mandate they give us, including him."
The Prime Minister accused Blackford of "defeatism and pessimism" on the future of the UK.
He said: "If we can deliver a fantastic, sensible and progressive Brexit, which I believe we can, and the whole United Kingdom comes out, as I know that it will, what happens then to the arguments of the Scottish National Party?
"Will they seriously continue to say Scotland must join the euro? Will they seriously suggest that Scotland must submit to the entire panoply of EU law?"
Earlier, Johnson said he still believed a new agreement could be struck with the European Union - one that did not include the Irish backstop.
He told MPs: "I would prefer us to leave the EU with a deal - I would much prefer it.
"I believe that it is possible even at this late stage and I will work flat out to make it happen.
"But certain things need to be clear: the Withdrawal Agreement negotiated by my predecessor has been three times rejected by this House.
"Its terms are unacceptable to this Parliament and to this country."