Neilson replaces Nucleus co-founder Philip Martin who left the platform last year to join F&C as head of proposition for its UK retail business.
Martin, who was business development director at Nucleus, co-founded the platform in 2006 and left in June last year.
Neilson will be take overall responsibility for the business development and account management functions as well as the wider strategic development of the company. He will also become a member of the executive team, reporting directly to Nucleus chief executive David Ferguson.
Ferguson says: “We are thrilled to welcome Barry to the Nucleus team. With 2010 shaping up to be a pivotal year for the platform industry his knowledge and understanding of the IFA market will be of tremendous benefit to the business and our member firms as we look to accelerate our growth and development.”
He adds: “This also completes the executive team with a view to building on our momentum as we approach break-even and continue to grow our market share.”
Last week Nucleus appointed former Standard Life Savings chief operating officer Aileen Mathieson as its new chief financial officer.
Mathieson replaces Neil Howitt who left the platform in November.