Baltimore-based Brown Advisory launched in London in 2008 and currently manages $2bn of assets for UK and European institutions.
The firm grew out of Alex Brown & Sons, founded in 1800 and the oldest US investment bank. Brown Advisory became independent through an employee-led buyout in 1998.
Brown Advisory focuses on investing in US equities and its client base includes wealth managers, private banks, charities and pension funds.
Kitty Parry, MD of Templars, said the agency would be 'helping Brown Advisory to demonstrate to investors that it offers an excellent route to investing in the US'.