Devine has been at Engine-owned MHP since its formation in 2010, having initially joined Mandate, one of MHP’s predecessor companies, in 2004.
London-based MHP, which employs around 175 people, had a difficult 2014, with fee income falling 14 per cent that year to £16.5m, according to PRWeek’s annual Top 150 list. However, more positive news in 2015 and 2016 has included new account wins including transport provider Arriva, along with appointments such as former minister Paul Burstow.
Speaking to PRWeek, Devine called MHP a "fantastic business", adding: "We had a tough time in 2014, we made difficult decisions and we’ve been really getting things back on track. I feel now it’s time to go and do something new, and look at some new challenges.
"Porta is a new company that’s got lots of fascinating companies within it; it needs to be brought together a bit better. I feel Porta provides a fantastic platform."
PRWeek understands Devine’s successor has not yet been lined up.
In a statement, Engine CEO Debbie Klein said: "During his four years as CEO Gavin has led the development of a fully-fledged integrated offer, and built a strong, award-winning team very well positioned for long-term growth.
"I am delighted that our clients and staff benefit from a strong established leadership team including MHP chair Sally Costerton, and I will continue to work closely with them as we transition to a new leader for MHP."
Devine said: "I am very proud of MHP’s achievements, and the role I have played as chief executive over the past few years. Our commitment to deliver the highest quality, integrated communications is bearing significant fruit in terms of new client wins and a host of industry awards. I am very much looking forward to my new role knowing that I leave behind an MHP team that is stronger than ever and fantastically set up for continuing healthy growth."
Porta – which owns PR shops including Newgate, Thirteen, Redleaf Communications and Publicasity – said Devine’s role will involve overseeing the "continued integration of the group, ensuring that the various divisions collaborate effectively and take advantage of all available synergies".
He will also play a "leading role in the further development of the public affairs and corporate communications capabilities within the group".
His appointment follows that of Steffan Williams, former partner at Finsbury and co-founder of Publicis-owned Capital MSL, as group MD in September. It comes as the group targets further expansion. In a trading statement released last month, Porta said it is lining up "a number of potential acquisitions" for this year.
Porta CEO David Wright said: "We are building a significant integrated consultancy that has the specialist expertise necessary to service the communications needs of major organisations under one roof. Gavin's appointment will help us to build on the considerable progress that we have already made in building an integrated offer and winning more blue chip clients."