The Sky News anchor, Niall Paterson, repeatedly asked Tim Farron if today's anti-Brexit London march had any actual purpose.
The Liberal Democrat leader, who is leading the pro-European charge in British politics, struggled to specify the aims of today's protest march, organised by Unite for Europe.
Thousands of Remain voters flooded onto the streets of London today to protest against the triggering of Article 50 this coming week.
However, in an astonishing interview, Paterson persisted in asking Mr Farron what hope any of those attending the march had of having any real impact.
Niall Paterson repeatedly asked Tim Farron if today's anti-Brexit London march had a purpose
The anchor asked: "Given that Article 50 is going to be triggered, given that we will be leaving the EU at some point, what is the point?"
The Liberal Democrat claimed that thousands of people wanted to "express their identity as Europeans".
Paterson hit back and asked: "But the referendum is over. We don’t need a march through London to illuminate the fact that the vote was pretty much fifty-fifty.
"Again, I'm going to ask, what do you hope to achieve? What will come of this?"
The news anchor continued: "Isn’t this just a little after the fact? Would it have been better to have made these arguments before the vote itself?"
The Liberal Democrat leader, who is leading the pro-European charge in British politics, struggled
Between 25,000 and 10,000 are attending the march
Mr Farron responded: "Theresa May's Brexit is not enacting the will of the people, it’s turning and twisting the will of the people.
"We believe we must have a vote on the destination of Brexit.
"It's also about sending a message to Europe that we do not want to cut ourselves off from the continent."
Extra police officers were in place for the march, as between 25,000 and 100,000 showed up to voice their despair at Brexit.
The Unite for Europe march will end with a rally in Parliament Square, a scene of floral tributes to victims of Wednesday’s terror attack.
The Unite for Europe march will end with a rally in Parliament Square Remoaners Club: These people hate Brexit! Mon, January 16, 2017
Remainers are finding it hard to accept Brexit.
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Organisers said in a statement: "We will not be intimidated. We will stand in unity and solidarity.
"We will march on the heart of our democracy and reclaim our streets in honour and respect of those that fell.
"We will be observing a minute of silence and remembrance at the start of the rally.
"We would encourage all attendees to bring with them some symbol of respect and to act in the appropriate fashion on the day."
Alongside Tim Farron, the former deputy Prime Minister Nick Clegg, Labour MP David Lammy and Green co-leader Jonathan Bartley are also expected to address the rally.