Catherine Miles has been appointed director of fundraising at the animal charity Battersea.
Miles, who left her role as director of fundraising and engagement at Breast Cancer Now at the end of November, will join Battersea in January.
Claire Horton, chief executive at Battersea, said: "Catherine has a truly impressive track record as a high-achieving fundraiser across many different areas of fundraising.
"She is highly regarded across the charity sector and I very much look forward to her joining us here at Battersea."
A spokesman for Breast Cancer Now said Miles’ departure had not been "directly related" to the planned merger.
Delyth Morgan, chief executive of Breast Cancer Now, said: "Catherine led the fundraising directorate during a very high-profile time for the charity and played a significant part in Breast Cancer Now’s development and growth.
"I’d like to take the opportunity to thank Catherine for her contribution to Breast Cancer Now and wish her all the best for the future."
Miles said she could see Battersea had "great potential for continued growth and development" and was looking forward to working with the staff and animals there.
The charity has also announced that its former finance and corporate services director, George Ruiz, is set to return to Battersea after two years as director of resources at Prostate Cancer UK.
Ruiz, who was previously at Battersea between 2013 and 2017, said: "There’s something special about Battersea and I’m very much looking forward to returning.
"So much has been achieved in terms of growth in the time since I have been away, and I’m excited to pick up the reins again working at a charity I understand and care so much about."
Horton said she was confident that both Ruiz and Miles would "be tremendous assets to Battersea", which was due to launch a new strategic plan in 2019.