"There is no way that Boris Johnson is going to agree to a second independence referendum, and I certainly hope that [Scottish First Minister] Nicola Sturgeon understands that. She has to be as strong as Boris Johnson is. She has to be as stubborn as he is. Johnson has no legal, ethical or political right to stop Scotland getting a second independence referendum," Penman said.
The statement comes a day after Sturgeon warned Johnson against blocking a new referendum on Scottish independence as a fresh poll found a majority would now vote in favour.
Penman went on to stress that a no-deal Brexit scenario was increasingly likely, claiming Johnson had effectively destroyed any chance of reaching some form of an amicable withdrawal deal with the European Union.
Economic dislocation, he argued, was now a likely outcome, something that would fall heavily on Scotland and the United Kingdom as a whole.
"I don't even think there's a likelihood [of a no deal], I think he's [Johnson] shuffled off any pretence of wanting to get a deal in Europe. I think it's absolutely certain now that he's going to get a no-deal. Every economist worth their salt tells us that that's going to be disastrous for ordinary people. It's going to be a terrible result and will also hasten a recession," Penman stressed.
He also claimed it was perhaps a mistake for the Scottish National Party (SNP) to have allowed itself to become arguably distracted by the 2016 referendum on membership of the European Union. Rather than fixating on remaining within the European Union, he claimed, the SNP should have placed a priority on pursuing another referendum on independence from the United Kingdom, something that could have then permitted Scottish voters to decide on continued membership of the European Union on their own terms.
Commenting on recent remarks made by the former first minister of Wales, Carwyn Jones, who himself warned at the weekend that a "bad Brexit" could lead to the break-up of the United Kingdom, Penman also argued a "no-deal" scenario could strengthen pro-independence sentiments in Wales, claiming Johnson's alleged unpopularity would likely prompt widespread opposition across England itself.
"I would certainly agree with that comment by Jones. There is no real reason for anyone in Wales to want to remain part of a UK that is led by Boris Johnson. Why would they want to be a part of that? Also throughout England, there's going to be resentment and a strong reaction to a Boris Johnson government," he claimed.
Johnson, who has repeatedly stated the United Kingdom will exit the European Union on October 31 without a deal, if necessary, is believed to be under increasing pressure following lukewarm receptions last week in Wales, Northern Ireland and Scotland, with the latter visit involving the Prime Minister being jeered by the public when meeting with Sturgeon.