Hi Colinba,
That is probably about right, but things have changed a bit in the UK; due to better MRI imaging in the last five years, they now do less biopsies, but they are better targeted at those likely to have cancer. So the figure of 50% may be outdated, and now it might be 60%.
About 70% of men at that age will have some signs of cancer in the prostate and it just sits there quite harmlessly for decades. So don't be too worried about the fact he has a biopsy, and don't be too worried about a positive result. A prostate cancer diagnosis is not a death sentence.