David Cameron has applied to register the Tories as the “Conservative and Unionist party” across Britain.

The move comes as the Prime Minister flies into Scotland to address the Scottish Conservative conference.

There he will hammer home the message that his is the sole political party willing to stick up for the Union in Scotland.

With the collapse in support for Labour, Mr Cameron will tell the gathering in Edinburgh that the Tories are “now the only party that can challenge the SNP”.

The Conservatives are the only one "fit to expose these spendthrift, out-of-touch, dogmatic, inept nationalists for what they really are," he will claim.

The Tories are keen to capitalise after both the Scottish Labour and Scottish Lib Dem leaders suggested their MSPs could campaign for independence in another referendum.

The application to the elections watchdog would allow the Tories to use the name “Conservative and Unionist" on ballot papers in May's Holyrood elections.

Electoral rules mean it could still appear as the shorter “Conservative Party” on ballot papers south of the Border.

However, the change will be seen as a symbolic commitment to the Union, although it could trigger a backlash from some of Mr Cameron's backbenchers.

As well as having an official name, all political parties are required to register a chosen name with the Electoral Commission.

Currently in Scotland, England and Wales the Tories are registered as the Conservative Party, according to the Commission.

However, alongside a name parties can also register a series of descriptions.

At the moment for the Tories these include Scottish Conservative and Unionist, the Conservative and Unionist Party and David Cameron's Conservatives.

In Northern Ireland, where the system operates slightly differently, the party name is already registered with the Commission as the Conservative and Unionist Party.

Mr Cameron's party applied for the name change on February 26, just days after the Prime Minister announced the date for his European Union referendum.

Strict rules for the Holyrood vote state that constituency candidates can use only their party’s registered name on the ballot paper.

List candidates must also use their party name first, although this can be followed by a registered description.

The rules were tightened following controversy in 2007 when the SNP used the slogan 'Alex Salmond for First Minister’ on ballots.

At the conference today, Scottish leader Ruth Davidson will seek to present her party as champions of the NHS, demanding that spending on health rises by at least two per cent.

She will use her speech to highlight figures showing health spending rising faster in England than in Scotland.

In his address, Mr Cameron will accuse the SNP of being the “establishment” and mention Nicola Sturgeon’s family.

He will say that Scotland is in danger of becoming a one-party state, accusing the SNP of a litany of failure on pupil attainment, college student numbers, help for poorer university students and health spending.

He will also say hit out at the “mess of the law that bans football songs”, the merger that created Police Scotland and the Named-Person policy.

And he will criticise the "abolition of Right to Buy – yes, even though Nicola Sturgeon’s family benefited from it, she’s saying that you can’t."

“And it falls to us, the Conservatives, the only party fit to expose these spendthrift, out-of-touch, dogmatic, inept nationalists for what they really are."