You should be aged between 18 and 62, with UK, or EU citizenship. There are however relaxations, like you have indefinite leave to stay in the UK. You need to have lived in the UK continuously for the past three years. You should have security clearance and clearance of any previous convictions. You should have good physical capacities and good eye sight.

Your background will be thoroughly checked before you can join as a prison governor. Your experience in armed forced or police will also be helpful, while applying for the post of Prison Governor. After you are absorbed as a Prison Governor, you can get promoted to higher ranks.

You will need to pass the written tests, which are part of selection process. Unlike in several other services, you can reach higher ranked positions in relatively shorter time. You can also find employment in private prisons operated by companies. The exact entry requirements at such places can be variable.