ONLY a No vote in the referendum will preserve the devolution settlement that Scotland owes to the late Labour leader John Smith, the shadow foreign secretary will argue this week.

In his first outing for the pro-Union Better Together campaign, Douglas Alexander will say Smith wanted a strong Scottish Parliament, but also the strength and security of the UK.

Tomorrow's event in Edinburgh, on the 20th anniversary of Smith's death and the 15th anniversary of Holyrood's first sitting, marks a ramping up of Labour efforts on behalf of Better Together, and follows a recent speech for the campaign by former PM Gordon Brown. Alexander, the MP for Paisley and Renfrewshire South, will claim Smith saw a constitutional change not as an end in itself, but as a means to end poverty, injustice and inequality.

He will say: "John Smith spoke frequently of devolution as the settled will of the Scottish people.

"For John, a devolved parliament was not just an icon of Scottish identity but also a workshop for social justice. On September 18, the legacy of John Smith will be on the ballot paper."

Smith, who died of a heart attack aged 55 in 1994 after serving as Labour leader for just two years, is often spoken of as one of the best Prime Ministers Britain never had.

Alexander will say of him: "Scotland made John Smith. And as a result he loved Scotland …extravagantly.

"Like so many of us he was a patriot - but he was never a narrow nationalist.

"Those of us who followed John, those of us sustained by his memory and inspired by his politics, understand that the progressive and the positive choice for us in September is a vote to stay together with our friends, families and workmates from across the UK.

"Let us reject - as John did - the Nationalists' plea to separate Scotland from the United Kingdom.

"And let us embrace John's better and bigger vision - a people united, Scottish and British, and a powerhouse parliament able to separate Scotland from poverty."

In response, Yes Scotland said: "More and more Labour voters are realising that the Scottish Parliament offers a better vision and a better way of doing politics than Westminster.

"With independence, Holyrood will no longer have to focus on mitigating harmful policies set by the UK Government and instead focus on creating a fairer and more just society."