LONDON—Grayling is merging its UK brand practice with Huntsworth sibling firm Atomic, following a review of the firm's operations in the country.

The move will see Atomic UK head Daniel Cohen take on the role of global head of brands at Grayling, overseeing a team of 25 in London. Grayling's brand business will now be known as Atomic in the UK.

A Grayling spokesman said that the firm's restructuring is now complete, but declined to confirm how many redundancies had been made as part of the process. The specific merger with Atomic, he added, would not result in any layoffs.

The merger follows a similar move in the US, where Grayling integrated Atomic in 2013. Hunstworth acquired Atomic in 2011.

"The merger signals Grayling’s commitment to delivering high impact, content rich campaigns for brands across our network of eight UK offices, as well as globally," said Grayling UK & Ireland MD Sarah Scholefield.

Grayling's UK operation has seen considerable flux in recent months, with CEO Alison Clarke departing in June.