NICOLA Sturgeon will be faced with filling an “important gap” in her Cabinet when Michael Russell steps down from Holyrood next year, according to prominent figures in the SNP and leading European experts.

The Constitutional Affairs and Europe Secretary announced he will not be fighting the Scottish Parliament election in May next year after first being elected as an MSP in 1999.

Giving her reaction, director of the Scottish Centre for European Relations think tank Dr Kirsty Hughes pointed to Russell’s work presenting Scotland’s case for independence to figures in Brussels.

She also highlighted Russell’s role in demanding Theresa May and Boris Johnson should take account of Scottish Government proposals for Scotland to have a special relationship with the EU.

READ MORE: Michael Russell to stand down ahead of Holyrood 2021

“Mike Russell is very well known in Brussels and wider EU circles, for setting out the Scottish Government’s views on the EU and independence in the EU, not only on Brexit, so his departure will leave an important gap to be filled,” Hughes said.

“He has also played an important part both in fighting against Brexit and in contesting the May and Johnson’s governments’ failure to seriously consult with the devolved administrations throughout the Brexit process so far.”

She added: “The Scottish Government needs to invest in making sure that there is more in-depth EU expertise and and more relationship-building with the EU (both Brussels and member states) from across the Scottish Government not just in the Brexit and Europe dossiers.

“It could also usefully strengthen the way it uses the more junior Europe minister position – a role that seems to rotate almost annually, giving its occupant no serious time to develop European networks.”

Anthony Salamone, a political analyst and EU expert, said Russell had been “ a powerful advocate” for Scotland’s European interests.

“Mike Russell has been the Government’s central figure on Brexit since the early days of the EU referendum result,” he said. “In his interactions with the UK Government, the EU and its member states, he has been a powerful advocate for Scotland’s European interests.

“At home, he has been responsible for the monumental task of preparing Scotland for Brexit as much as possible, which has required effective coordination across the whole of government.”

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He added: “Speaking from experience, I know that he has been dedicated in listening to and engaging with anyone and everyone in Scotland who has had interests, concerns and views on Brexit and Scotland’s future. While he will leave big shoes to fill, his successor in government will undoubtedly benefit from his advice and expertise.

“Following the recent reshuffle, the Government now has a single cabinet secretary responsible for the constitution and European and external affairs. This portfolio makes sense and should be maintained. With a new referendum on the horizon, the Government should continue to increase its engagement in the EU and beyond.”

Deputy First Minister John Swinney tweeted: “I am very sorry that @Feorlean [Russell] has decided not to stand again ⁦@ScotParl. We have worked together for over 30 years and he is a much valued colleague and friend of mine. He still has much to give so all good wishes for what lies ahead.”

READ MORE: How Michael Russell rose to the top of the SNP government

Alyn Smith, the SNP spokesman for international affairs, said: “Michael has put in an incredible shift for Scotland, latterly fighting for Scotland in Europe where in Brussels and in London he was pitch perfect. He is a true internationalist and has been a credit to our government.”

Kevin Pringle, former SNP communications director, also gave his reaction. He told The National: “Mike Russell has been integral to the success of the modern SNP, and it was a joy to work with him as far back as the 1990s when he was the party’s chief executive.

“He has always brought his formidable intellect and cultural hinterland to politics, but also an enthusiasm for the big jobs and a sense of fun, which is important.

“Mike has made a superb contribution to the work of the Scottish Government, above all in his current role of articulating the case for Scotland as an independent European nation; during the Brexit process, he vastly outshone his ministerial counterparts at Westminster. I completely understand why he is stepping down from public office, but I’m sure he will remain a key player within the SNP and wider Yes movement.”