The merger, completed this month, was driven by the changing financial climate, said Emma Halls, the chief executive of the PCRF. Halls will remain as chief executive of the new charity, which will have an income of about £2m a year.
"There were a number of similarities between the two organisations," she said. "We were formed at similar times in the early 1990s, and we’ve held joint fundraising events in the past. We’ve even tried to merge before, but the timing wasn’t right.
"Now the trustees felt we could increase our profile and reduce confusion among donors and the researchers we fund by joining forces."
Amanda McLean, chief executive of Prostate UK, has already left to become chief executive of the Institute of Fundraising. Halls said there would be no other redundancies.
"PCRF had five staff, and Prostate UK had 10," she said. "There was very little overlap, though, so all staff will continue."
She said the two organisations had moved to Prostate UK’s offices in Putney, south-west London, and staff were already working together, but it was taking time to combine back-office functions.
"We had two JustGiving accounts, two sets of auditors and different year-ends," she said. "It takes time to bring all those things together."
The charity will be launched formally in March next year.