Smithfield, which has a client list that includes Rothschild, Goldman Sachs and Investec, is to maintain its separate brand identity within Edelman and remain at its office in Aldersgate Street in the City.
The agency, formed in 1998, currently employs 20 consultants. It has worked on recent deals including advising Ferrero on its acquisition of Thorntons and Brookfield on its successful offer for Songbird/Canary Wharf, as well as the acquisition of Center Parcs.
Williams told PRWeek: "They do quite a lot of deal work and they’re very strong in financial services, and had a decent recent run in M&A as well.
"My overall strategy is [to be] an integrated communications firm that is staffed by deep specialists in the key verticals that are important when thinking about corporate reputation. This is, in my mind, one of the last pieces in the jigsaw, and it allows us to advise our clients on all aspects of reputation."
Discussing the Edelman business globally, Williams added: "We’ve been investing in financial PR in the US. We have also been doing the same in Asia. Now with this capability in London, we’re able to really offer a global financial PR solution."
Asked if the acquisition is more of a one-off rather than part of a general acquisition plan, Williams said: "I think that’s right."
The acquisition will see Smithfield MD John Kiely join Edelman’s executive committee, with Smithfield’s directors joining the leadership team. Williams said no redundancies were planned. "We’re not doing it for synergies or costs savings. We think this is a business we can help grow – that will mean investing in it."
There are also no immediate plans to add the Edelman branding to Smithfield. "In time I’ll look at that but for now it will remain 'Smithfield'," said Williams.
He said Kiely and his team are "a brilliant cultural fit with Edelman".
"Their unflappable, quiet, modest approach belies a deep knowledge and understanding of the financial services sector, an exceptional roster of clients and long-term relationships. We believe there is a very big opportunity for Smithfield to grow – not just in the UK, but by working with the Edelman network, bringing its expertise to bear on a global scale."
Kiely said: "Being part of a highly successful and fast growing global business will be hugely attractive for our clients and our people as there is a clear benefit from the broader geographic reach and the complementary services that Edelman offers.
"We have been impressed by the Edelman team, we like their approach and commitment to develop a leading financial communications and capital markets offering with a strong financial services bench. We are looking forward to working with our new colleagues to grow the business both in Europe and internationally."
The sale price has not been disclosed.