INDYREF2 is not the only way to achieve independence, a prominent SNP politician has said.

Writing exclusively in The National today, Joanna Cherry says that having a Plan B is a “no brainer”, and outlines some of the possible alternative options for Scotland.

She argues that there is, “in legal and constitutional terms”, a clear precedent for leaving the United Kingdom without having had a referendum.

The SNP are supposed to be debating a so-called Plan B for independence – what to do if Westminster refuses consent for a referendum – in an internal “National Assembly” later this month.

READ MORE: Joanna Cherry: History shows a referendum is not the only route to independence

Ahead of that gathering, Cherry says that while the “easiest and best way” to achieve an independent Scotland is through a Section 30 order and a majority Yes vote, those who hope for an exit from the Union “would do well” to remember that Ireland went down a very different route.

Although Cherry cautions that the violence that came before the Republic of Ireland negotiated independence is something that “no-one wants to replicate”, she says the resulting treaty “shows that a constituent part of the UK can leave and become independent by a process of negotiation after a majority of pro-independence MPs win an election in that constituent part”.

She continued: “Prior to the advent of devolution it was thought that a simple majority of pro-independence Scottish MPs would be sufficient to open negotiations on independence. Mrs Thatcher appeared to endorse this view in her memoirs.”

Devolution in Scotland is just over two decades old. The Edinburgh Parliament was opened in 1999. However, the Union predates this by almost 300 years, having started in 1707.

With this in mind, Cherry says that to look at routes to independence only through “the prism of devolution” is “short-sighted”.

Yes to Scottish independence has been the majority position in Scotland for the last 17 polls in a row. More than one poll has put the support at 58% with Don’t Knows excluded.

READ MORE: Michael Russell told Australia Scotland wants indyref2 this year

Cherry argues that these “unprecedented levels” would never have been achieved “had we and those who went before us not been prepared to be radical”.

She adds: “It is foolish and dangerous to rail against having a plan to do things differently, should it be required.”

The international community and Government in Westminster will only be further convinced that the only legitimate way to independence is through a referendum if that is what the SNP also say, Cherry says.

As such, she argues it is “a no-brainer” that having a legitimate Plan B to achieve independence is necessary. On January 24, the SNP’s virtual National Assembly will take place to discuss the tactics and strategy on the route from here to Independence Day.