Scotland's leading expert in constitutional law is to become an official aide to Alex Salmond, in a team of special advisers.

Professor Sir Neil McCormick is to provide unpaid, part-time advice on Europe and external relations, though the former SNP MEP and MP, who is an Edinburgh University legal expert, has expertise that may also be vital in handling constitutional issues within the United Kingdom.

The 66-year-old regius professor of public law is part of a slimmed-down team of political special advisers for the SNP ministerial team announced yesterday by Finance Secretary John Swinney.

The administration highlighted the reduced cost of the team. Whereas the previous executive team had 12 special advisers - nine for Labour and three for the LibDems - this group has six full-time and three part-time advisers, one of whom is unpaid and another is employed for only two months.

The salary bill totals £425,200, ahead of an upgrade backdated to April 1, whereas the comparable figure for the outgoing team was £772,400 - a reduction of 45%. One of the staff is in the top salary band, ranging up to £100,900, while three are in an earning band up to £81,000 and three more are on less than £49,000. Three are aged under 27.

A key figure in the team will be Duncan Hamilton, 33, the former Highlands and Islands MSP who stood down in 2003 to train as an advocate. His contract will let him continue in private legal work though he is expected to spend by far the larger part of his working time as political adviser to the First Minister.

A short-term post has been given to Jennifer Erickson, 30, an American management consultant who first got to know Mr Salmond as a Westminster intern, and returned to work on the campaign this year, winning business support for the SNP. She is to work for only two months in setting up the new Council of Economic Advisers, before returning to her home in Washington DC.

The rest of the special adviser team is made up of those close to Mr Salmond and his deputy, Nicola Sturgeon, while in opposition. While Mr Hamilton works directly for Mr Salmond, Noel Dolan, 55, continues as Ms Sturgeon's own policy adviser, on health as well as the policy he drew up on local income tax..

Stephen Noon is senior adviser and will specialise in John Swinney's finance and sustainable growth portfolio. He has his own deputy adviser, John McFarlane.

Two of the team are spin doctors - Kevin Pringle, 39, a press officer for the SNP from 1989, and Jennifer Dempsey, 25, who brings events promotion experience from the music industry. She will also work on parliamentary liaison, along with Geoff Aberdein, 24.

A spokesman for the First Minister said: "Along with the rest of this talented team, Professor MacCormick and Duncan Hamilton bring a wealth of skills and experience to the job."