Our Scotland Political Editor Peter MacMahon spoke to the Prime Minister during his visit to the Scottish Conservative Conference.
Watch the full interview on independence - and how it could affect the border - here:
David Cameron has been speaking to ITV Border's Scotland Political Editor Peter MacMahon at the Scottish Conservative Party conference.
When asked whether there would be border controls between Scotland and England this was Mr Cameron's response.
David Cameron has condemned Scottish nationalists as "wrong and irresponsible" for dismissing warnings about the political consequences of the upcoming referendum as a "south of the border conspiracy".
Addressing the Scottish Conservative party conference, the Prime Minister said the warnings about an independent Scotland's currency and place in Europe were necessary with citizens ready to make a "major life changing decision".
David Cameron has said his promise to make devolution work better for Scotland is not a consolation prize for Alex Salmond if the nation votes to stay as part of the UK.
Mr Cameron was addressing his Scottish party members at the Edinburgh International Conference Centre.
David Cameron addresses Scottish Conservative Party conference in Edinburgh
David Cameron told the Scottish Conservative Party conference in Edinburgh that a 'no vote' can mean further devolution and more power to the Scottish people.
– David Cameron, Prime Minister
"Let me be absolutely clear: a vote for 'no' is not a vote for 'no change'.
"We are committed to making devolution work better still.
"Not because we want to give Alex Salmond a consolation prize if Scotland votes No, but because it's the right thing to do.
"Giving the Scottish Parliament greater responsibility for raising more of the money it spends.
"So here's the re-cap: vote yes, that is total separation.
"Vote no, that can mean further devolution more power to the Scottish people and their Parliament, but with the crucial insurance policy that comes with being part of the UK."
David Cameron has told the Scottish Conservative Party conference in Edinburgh there will be 'no going back' if Scotland vote yes for independence.
– David Cameron, Prime Minister
"Six months from now the day will dawn , the polling booths will open, the voters will come out and the people of Scotland will decide - stay or go.
"Stick with the UK or walk away.
"If the Scottish people vote Yes in September, then Scotland will become an independent country, there will be no going back, no second chances."
"We face a monumental battle to keep our United Kingdom together."
David Cameron will focus on his fight to keep Scotland in the UK as he opens the Scottish Conservative party conference later today.
He is due in Edinburgh, where he will draw on recent interventions from major businesses, such as BP and Shell, in the referendum debate.
Mr Cameron will attempt to tackle accusations of "scaremongering" over the country's future, saying he wants to "take that myth apart".
Speaking at the opening of of the Scottish Conservative party's spring conference in Edinburgh, the prime minister is expected to say the referendum is "a major life decision" that shouldn't be made without knowing the full consequences.
He is expected to add:
– Prime Minister David Cameron
And look at who's laying out those consequences: the governor of the Bank of England, the president of the European Commission, business chiefs from companies like BP and Shell; Alliance Trust and RBS; Lloyds, Barclays - the list goes on.
These are not political puppets, they are serious, non-partisan figures.
So, the idea that these are empty warnings and political scare-mongering is a myth - and we owe it to the people of Scotland to take that myth apart.