NICOLA Sturgeon has secured the endorsement of the Scottish Parliament for a second independence referendum, only for the UK Government to throw new obstacles in her path.

After three days of debate, and knowing it would mean a constitutional fight with Westminster, MSPs voted 69 to 59 for the First Minister’s proposal for a new vote by spring 2019.

However the UK Government, which has said “now is not the time” for a referendum as the UK negotiates Brexit for two years, immediately hardened its stand, raising the prospect of more delays, potentially taking a referendum beyond the next Scottish election in 2021.

Tory sources have told The Herald they want to delay the issue past 2021 in the hope a pro-Union majority is elected at Holyrood and kills off any chance of another referendum.

Ms Sturgeon told MSPs she intended to approach the UK Government later this week about transferring referendum powers to Holyrood through a so-called Section 30 order.

Her plan is hold a referendum once Brexit terms are clear, giving voters a choice between Brexit in the UK and independence and a closer relationship with Europe.

Theresa May will trigger Brexit today by invoking Article 50 of the Lisbon Treaty.

The Prime Minister will tell MPs: “We are one great union of people and nations with a proud history and a bright future. Now that the decision has been made to leave the EU, it is time to come together.”

Ms Sturgeon said she agreed with Mrs May that now was not the time for a referendum - she wanted Scotland to have its say on Brexit “when the time is right”.

She told Holyrood: “I hope that the UK Government will respect the will of this Parliament. If it does so, I will enter discussion in good faith and with willingness to compromise.

“However, if it chooses not to do so, I will return to the Parliament following the Easter recess to set out the steps that the Scottish Government will take to progress this Parliament’s will.”

Options include publishing a referendum bill as part of efforts to build support for a Yes vote.

But the UK Government instantly refused to enter talks until after Brexit, and suggested an open-ended timetable to let people absorb the impact of life outside the EU.

Scottish Secretary David Mundell said the timescale could include "the Brexit process, the journey of leaving and people being able to understand what the UK's new relationship with the EU is".

He added: “We are not entering into negotiations on whether there should be another independence referendum during the Brexit process.

“We don't have a crystal ball as to how long that process will take. It will be a journey that will involve the negotiations with the EU, it may be a journey that involves transitional measures, it may be a journey that involves significant implementation time."

The UK Government’s Brexit White paper said new EU immigration policy, custom systems, and cooperation on criminal and civil justice could all require lengthy “phased implementation”.

A UK Government spokeswoman added: "It would be unfair to the people of Scotland to ask them to make a crucial decision without the necessary information about our future relationship with Europe, or what an independent Scotland would look like."

Interviewed on BBC Scotland last night, Deputy First Minister John Swinney repeatedly refused to set out what the Scottish Government’s next steps might be.

But one senior Nationalist told the Herald the goal was “winning hearts and minds”, perhaps publishing a refreshed case for independence and trying to influence opinion in Europe.

The source said: “The one thing that’s blatantly obvious is that the UK are not going to talk about a Section 30 order this side of a Brexit deal.

"Therefore the Scottish Government has to win over public opinion, so that by the time a Brexit deal is done, it’s politically impossible for the Tories to say no. No other strategy matters.”

Speaking after MSPs cheered and applauded the historic vote just after 5pm, Ms Sturgeon said the will of the elected parliament “must now be respected”.

She said: “The mandate for a referendum is beyond question, and it would be democratically indefensible and utterly unsustainable to attempt to stand in the way of it.

“Every other nation in the EU will have a say on the terms of Brexit, and on how it impacts Scotland. The people of this nation cannot and must not be the only ones denied a say.

“The people of Scotland are sovereign, and they will be given a choice on their own future.”

Opposition leaders pointed out Ms Sturgeon had ignored several Holyrood votes, and said it was hypocrisy for her to say the UK Government must obey when she didn’t do it herself.

Scottish Tory leader Ruth Davidson said the decision was “deeply regrettable”.

She said: “We have made it clear: now is not the time to go back to another divisive referendum. Not when there is no public support for one.

“Not when the SNP said the last referendum would be once in a generation.

“Not when we have no clear picture as to what either Brexit or independence will look like.

"We will continue to oppose a second referendum every step of the way.”

Scottish Labour leader Kezia Dugdale said Scotland “doesn’t need or want a second independence referendum” and there was no evidence it was the will of the people.

However, while maintaining her opposition to independence, she also appeared to soften her refusal to accept a referendum in the current parliament, saying that if Scots wanted one after Brexit “then it isn’t the job of the UK government to stand in the way of that”.

She said: "There absolutely should not be another independence referendum until after Brexit. We have no idea what Brexit looks like, or how it will impact our economy and families in Scotland.

“If there is to be another vote, the people of Scotland deserve clarity on what they are being asked to vote on. This cannot be a stitch-up between Nicola Sturgeon and Theresa May.”

The motion passed at Holyrood included an amendment from the Scottish Greens calling for EU citizens to vote in the referendum and laying blame on the Tories for a “hard Brexit”.

Green MSP Ross Greer MSP said: “Giving the people that choice in autumn of 2018 - when the details of the deal are known – would give us the time to begin extracting Scotland from this mess before the Tories hurl Britain off the Hard Brexit cliff – if that is what the voters choose.”

Scottish LibDem leader Willie Rennie MSP said: “Nicola Sturgeon is in an absurd position as she is using the EU to get her referendum but the referendum won’t get the EU. It shows that the EU was just an excuse and that it has only ever been about independence.”