It follows Dairy Crest's £86.5m acquisition of the Uniq-owned St Ivel business last month.
St Ivel's spreads marketing director Ceri Bennett will become his second in command. Her job title has not yet been finalised.
Tolley takes responsibility for a portfolio that sees St Ivel brands such as Utterly Butterly, Vitalite and St Ivel Gold join Dairy Crest brands Clover and Country Life, with a combined marketing budget of more than £7m.
Tolley said that Bennett's responsibilities will include integrating the brand portfolio and aligning the agency roster. Abbott Mead Vickers BBDO currently handles advertising for St Ivel's brands. Grey handles advertising for Dairy Crest's brands, including television for Clover and the shakes drink Frijj.
Tolley said each individual account would be looked at in terms of its agency relationship, but added that it was too early to comment on a review.
Dairy Crest spent £2.3m on marketing over the 12 months leading up to September this year according to MMS. St Ivel spent £4.1m during the same period.
In June of this year Grey was appointed to handle the £2.5m launch of Dairy Crest's olive oil and buttermilk spread Argento. TV advertising for the brand broke last month with a 20-second ad called 'blonde'.
Dairy Crest acquired the licensing rights to St Ivel's butter brands two years ago before acquiring the entire spreads portfolio last month from Uniq.
Uniq had earlier sold its Shape and St Ivel yoghurts business to Danone in order to focus on convenience foods. Alongside Bennett, 15 other St Ivel marketing staff moved over to Dairy Crest last month (Marketing, October 10).
Last year Dairy Crest recorded profits of £73.7m, while St Ivel Spreads achieved a profit of £12.6m.