Probyn grew up in rural Jamaica, his father was James Mortimer Aitken and his mother, Esther Rebecca Aitken (nee Holmes). He had six siblings – Cis, Oret, Evris, Lil, Merle and Sadyvet. As a child, he was known as “Biggie”, and over time this transgressed to “Big P” or “Uncle P”. He married once, to Rosalie Alethea Aitken (nee Hinds). They had two children together, Dianne and Edward. The marriage lasted from 1962 to 1988, but they lived separately from 1970 onwards. Probyn also had two children from two other relationships, Patrice and Allison. His grandchildren are (in age order) Eleanor aka "Elle", Joshua, Emma and Oliver.