The deal sees £40m ($55.5m, €45m) of assets under advice added to Old Mutual Wealth’s financial planning arm.
A&M’s clients will be serviced from OMW’s London office.
Established in 2015, OMWPCA has expanded rapidly through a spate of recent acquisitions and now employs more than 50 financial advisers in six regional hubs across the country.
Over the first half of 2017, Old Mutual Wealth’s financial planning unit accounted for £600m of the UK platform’s net inflows.
OMW oversees £131.3bn in customer investments as of 30 September 2017.
Commenting on the firm’s latest acquisition, Dominic Rose, director at OMW Private Client Advisers, said: “This is a fantastic opportunity to grow our business and give A&M’s clients continued access to quality, face-to-face financial planning.
“A&M is a firm that has focused on providing a personalised service in London and the south-east of England, making it a good cultural fit with Old Mutual Wealth Private Client Advisers and our commitment to providing exemplary client service.”