Marketing and PR group Porta Communications announced a boardroom rejig on Friday as the company plans to merge two parts of its UK operation.
Group chief executive Steffan Williams has left the group with immediate effect and will cease to be a director by 5 May at the very latest.
Emma Kane, chief executive of Redleaf Communications, and Brian Tyson, managing partner of Newgate Australia, have been appointed as joint chief executives of Porta and will respectively manage the group's UK and Australian businesses.
Kane will be tasked with combining Newgate and Redleaf's UK operations as she founded the latter company in 2000 and successfully oversaw the integration of PR agency Polhill into the business in 2010.
Chairman John Foley said: "Redleaf has been a great acquisition for Porta and it now makes absolute strategic sense to combine the business with Newgate and create an enlarged business to capitalise on the expertise and proven track records of the exceptional people at both firms."
The combination of Newgate and Redleaf will spawn a company with over 100 employees and offices in London, Bristol, Cardiff, Edinburgh, Leeds and Manchester, while the wider Newgate network includes other offices in Europe, Australia, China, Singapore, Hong Kong and the Middle East.
Tyson, meanwhile, will continue his work with Newgate Australia, which has become the largest and most profitable part of the group since Tyson oversaw the conception of the business in 2013.
"In Australia, from start up five years ago with a core group of 8 people in offices in Sydney and Melbourne, the business now has more than 100 professional staff and opened additional offices in Canberra, Brisbane and Perth," said Foley.
"Together, Brian and Emma will give us the leadership we need on both sides of the world to help roll out an integrated offering in our major markets, by learning from each other, replicating the specialist skills and services that exist in some markets, and adopting best practice in all markets to the benefit of clients internationally," said Foley.
As of 0930 BST, Porta Communications' shares
were up 15.56% at 2.60p.