In her column last week, Lesley Riddoch made a number of key arguments in response to my article arguing the SNP should call to halt Brexit. Here, I will attempt to address her points.

1. The SNP has no influence

This is fatalistic. Across the UK, 54% now support Remain. Over a 100,000 people marched in London last Saturday for a “people’s vote” on Brexit. It got great media coverage. If Nicola Sturgeon had been on the stage in Parliament Square calling to halt Brexit, would the media have covered Vince Cable and Caroline Lucas but not her?

It’s worth recalling 2015, when Sturgeon’s rating was as high, after the General Election debates, as UK party leaders. Sturgeon calling to halt Brexit would be welcomed by Remain supporters across the UK, including in Scotland.

The SNP’s walk-out at Westminster did have impact. More importantly, appealing to the public across the UK does not require Tories to stop braying at Westminster when SNP MPs speak. It’s about opposition, trying to create momentum and being part of, and leading, the public debate. If opinion shifted to 58% or even 60%, pressure on May and on Labour would be huge.

But has Sturgeon really been trying to extricate the UK from Brexit? No, she’s been emphasising a “soft” Brexit together with defending the devolution settlement.

Airbus’s damning clarity last week on moving jobs and investment out of the UK, Saturday’s demo, the shift in the polls – there’s a growing dynamic against Brexit.

The SNP could be an influential part of that.

2. Independence is a way to escape Brexit

If Scotland became independent, devolution would be irrelevant but Brexit would still have very damaging impacts on Scotland – so why prioritise defending devolution over halting Brexit? Estimates for Ireland suggest a 7% hit to GDP from a WTO outcome – there is no Brexit “lifeboat”.

Brexit will also raise tough questions about a hard border between an independent Scotland and England – the Tories current quagmire over reconciling frictionless borders with a hard Brexit show that.

3. It’s up to the English if they want Brexit

There’s a slim Remain majority in England now too. One recent poll had London, Midlands/Wales, North of England all pro-Remain and only the south still Leave. That’s with little political lead from anyone.

Why leave it to the English to shift opinion further when it’s in Scotland’s interests that it shifts? The SNP should speak out – and then ask Ruth Davidson (left) and Richard Leonard why they aren’t.

4. Arguing for a people’s vote could be a hostage to fortune

The people’s vote campaign is run by a range of groups including Open Britain. The SNP could easily step ahead of this debate while constructively engaging with it. It could call for a halt to Brexit and a further public vote. With the risk of no deal growing, a simple repeat referendum could make perfect sense.

Nor is asking the English and Welsh – and indeed Scottish leavers too – to think again a hostage to fortune. If English politicians, after a Yes in a second independence referendum, wanted to ask the Scots to think again, they could do so. It’s just political debate – not a veto.

Michael Russell said on Sunday he wasn’t “hostile” to the idea of a repeat vote, Ian Blackford MP said the SNP had an “open ear” to it – both ring of remaining hesitant on the sidelines at a crucial moment.

5. A second EU referendum might be lost

If a second EU referendum were won, the damage to Scotland is stopped in its tracks. And independence in the EU would be more straightforward. If the vote is lost, or if a vote is refused, then the SNP will have done its best to halt Brexit. And it would be a clear rationale for a second independence referendum in response to that second Leave vote or no vote.

The next six months are crucial for the halt Brexit fight. The SNP can stand on the sidelines or it can give a lead: it’s time to choose.