Grant joined Cohn & Wolfe in 2011 from Weber Shandwick, initially as EMEA consumer lead. She was promoted to UK MD, while retaining consumer duties, two-and-a-half years ago.
Her appointment as UK boss of BCW was announced to staff last week. PRWeek understands that her exact job title is yet to be confirmed.
As UK MD of Cohn & Wolfe, Grant reported to Scott Wilson, who was named Europe and Africa president of BCW in March.
WPP announced the creation of BCW in February.
Burson-Marsteller UK CEO Stephen Day has since been made redundant. Around the same time, Burson parted ways with public affairs client Ineos, although a source tells PRWeek that this is the only major UK client to have been lost since February.
Few details of the merger's implementation in the UK have been announced, although PRWeek revealed this week that UK BCW staff should come under one roof in the Autumn.