A senior Nationalist has said Scotland could seek independence without the approval of Westminster to stage a referendum on leaving the UK.
Western Isles MP Angus MacNeil insisted the current push for independence must not "dither like the Jacobites in Derby" in 1745 as he addressed party delegates at the Autumn conference.
It comes after the SNP's Home Affairs spokeswomen at Westminster Joanna Cherry yesterday suggested independence could be declared through a general election victory for the SNP in Scotland, although this was today rejected by Nicola Sturgeon.
But it comes amid growing agitation among Nationalist for a more urgent approach from the SNP leadership to stage a second referendum on independence to save Scotland from Brexit, as tens of thousands marched through the Edinburgh at the weekend.
Mr MacNeil said today that the damage to the economy would see Scots GDP nosedive by either 6% or 8%.
He added: "It is not a fantastic situation for anyone to find themselves in - but we have a 26 month window to do something about it.
"We do know the window is likely to be March 2019 to March 2021."
Read more: Angus MacNeil calls for indyref2 within a year
Mr MacNeil pointed to weekend polls which support for independence could be at 50-52% in the event of a hard Brexit.
"That is without even campaigning - another 17% was added the last time we campaigned. This time when the SNP gets going there will be a lot more gained.
"If we can't make this under a Section 30 order, then we have to make it another way. We cannot dither at this point. We cannot be like the Jacobites in Derby who let the opportunity pass as they did in 1745 and 1746.
"We have to go forward."
He added; "As Theresa May said of the UK: `We joined as a nation state and therefore we must be free as a nation state to make the choice to leave.'
"Well Theresa May if that applies to the United Kingdom inn the EU, then it most certainly applies to Scotland in the United Kingdom."