Learmouth has worked at GSK for 23 years in a variety of positions including global head of comms and investor relations from 2006-2010. His last four years were spent as senior vice-president of developing countries (Africa and Southern Asia).
Olley has been a director at Brunswick for 11 years where he advised on a range of reputation management and comms issues including acquisitions, disposals, crises and listings, particularly in the private equity and consumer brands industries.
Earlier this year former MHP executive chairman Gay Collins joined Montfort and became a founding partner of the firm.
Montfort was founded by Nick Miles and Hugh Morrison in 2014. The duo launched M:Communications in 2002, growing it to become one of the City’s top PR firms with revenues of £14m.
Montfort founder Hugh Morrison said: "Montfort is evolving fast, attracting people of the highest quality and building a client base to match. We are grateful to all concerned for their unwavering commitment to Montfort’s future success."