I've always favoured the traditional recruitment cohort for the police; young men not academically gifted but physically fit and who not only won't settle for being clerks or shop assistants but who possess a self-confidence that their poor academic prospects would otherwise leave unexpressed. None of which is remotely equivalent to the 'barely literate' standard of many new plods described by Tom Winsor. If a policeman can't write fluently in cursive script, if he can only painfully and slowly form mis-spelt words in BLOCK CAPITALS, if his vocabulary is functionally limited, if he's unable to understand the most simple mathematical relationships, he's unfit to wear the uniform.
A policeman needs an ability to listen, to understand and to reason. He needs to be able to write statements quickly and fluently, to give evidence coherently. He needs to remember the Act and the section of the Act. He needs to understand basic abstract concepts such as probity, equity and stewardship. Above all he needs the self-confidence to carry out his duties without resentment of or fear of ridicule from more advanced citizens, and without sense of obligation. Literacy is a good indicator of many of these qualities. Without them, a policeman is just a security guard.