Hello, I am Keith, one of the experts on Just Answer, and pleased to be able to help you with your question.
Assuming that the green keeper is a salaried employee of the golf club then a free membership could well be interpreted as P11d territory at the subscription level value. If, however, it can be shown that use of the course in competitive play was essential to enable him to perform his duties, then it would no longer be a benefit in kind.
Some golf clubs eg Wentworth offer local people substantially reduced membership fees for limited access to the course. Were this the case here I suggest that a P11d situation is avoided as his limited access would pass the 'performance of duties' test.
I do hope that you have found my reply of assistance.
Thank you for your support.