Breast Cancer Now has cut staff numbers by a quarter since the merger, through a mix of redundancy and "natural turnover", in a bid not to duplicate job roles.

The charity, which launched in April after a merger between Breast Cancer Campaign and Breatkthrough Breast Cancer, originally had a combined staff total of 212, according to the last accounts of the separate organisations.

The charity would not confirm how many of its former staff were made redundant, but a spokesman did confirm that around a quarter of the original 212 had left.

Fiona Hazell, director of communications and engagement at Breast Cancer Now, said: “The intention of our merger has always been to create a breast cancer research charity of scale by bringing people, resources and ideas from both charities together in order to end breast cancer.

"However, using our supporters’ money as efficiently as possible has always been critical so where resources were duplicated, we have sought to reduce these, including making redundancies. Overall, including but not limited to redundancies, there had been approximately a 25 per cent reduction in posts through the merger process.”

In a blog written for the Guardian Voluntary over the weekend, Baroness Delyth Morgan (pictured), chief executive of Breast Cancer Now, explained that after the merger, the charity needed to “reduce its headcount”.

“While building a structure that would enable us to realise our strategic vision was crucial, saying goodbye to close colleagues – some of whom had been with our legacy organisations for over a decade – was really hard,” she wrote.

Morgan said however that “our staff needed little persuading of the rationale”, behind the staff cuts.

The merger of Breast Cancer Campaign and Breatkthrough Breast Cancer into Breast Cancer Now was originally announced in November 2014. Breast Cancer Now’s annual income is likely to be around £28.3m, based on accounts filed before the time of the merger.