The new entity formed from the merger of the two UK agencies will use the SEC Newgate UK name, and will employ 130 staff in eight offices across the country.
The holding company previously held a 60 per cent stake in public affairs specialist Newington. The price of the deal is £420,799, which will be paid to the former minority owners - Newington co-founders Mark Glover and Phil Briscoe - in six instalments every six months, starting from six months after the transaction completes.
Newington CEO Glover becomes executive chairman at the new combined entity.
Newington is to exit its Southwark office when its lease term ends in July. The agency's staff will move into SEC Newgate's existing City of London base.
The group said: "By the end of this year, it is intended that all agencies across the SEC Newgate group will transition to the SEC Newgate brand.
"This will enable advice to be delivered under one brand by over 600 professionals across six continents, providing clients with around-the-clock counsel and support, implementing campaigns locally, nationally and internationally."
SEC Newgate chief executive Fiorenzo Tagliabue said: “SEC Newgate is already a top 30 global communications group and clients are increasingly working with many of our agencies across multiple jurisdictions. We now feel it is time to simplify our story and operate under one brand while ensuring that we retain the entrepreneurial spirit and domestic insights that are the hallmarks of our success.”
Emma Kane, chief executive of SEC Newgate UK and deputy group chief executive, said: “The marriage of Newgate and Newington creates a fully integrated service across communications, advocacy and research, all under one P&L. Our new brand reflects our strong local roots, global reach and true entrepreneurial spirit. This is great news for our talented team of people and the organisations we partner with as our clients.”
Kane told PRWeek there is "no duplication" of any role brought about by the merger. "It's purely... in terms of property costs where there's significant saving."
Glover said: “We are delighted to be joining forces to create SEC Newgate UK. The whole is definitely stronger than the sum of the parts, bringing together award-winning teams across the full communications spectrum to deliver positive, winning solutions for our clients’ priority issues. We are excited about the significant opportunity we have as SEC Newgate UK.”
The group's UK agencies also include PR shop Publicasity and creative agency 2112. Elsewhere, it owns Engage Communications in Australia, and Cambre in Belgium, ACH in Spain, Kohl PR in Germany, Clai in France and Martis Consulting in Poland.
Kane told PRWeek that Publicasity will retain its name because it is a "standalone brand" entirely focused on consumer comms.
She said the next stage of transformation to one brand will come at the time of the group's financial results in the first half of the year, with the process completed by the end of 2021.
On recent trading, Kane said: "Everything is very much on track and in line with expectations. We're incredibly proud of our team on the performance delivered despite the very challenging environment."
Glover stated. "We've had a solid year, not a particularly spectacular one, but we're really looking forward to the synergies of working as one agency."
The group employs about 600 staff in 36 offices across six continents.
This article was updated on Monday morning with more information about the merger.