Like the Sikhs? https://www.independent.co.uk/news/uk/home-news/first-sikh-guardsman-to-be-given-permission-to-wear-a-turban-instead-of-a-bearskin-8374240.html
Now, that's a beard.
The Sikhs may have been recently given permission, but apparently it doesn’t apply to white Christians. The British press today has mentioned the beard issue and noted that Harry had to get permission from the Queen to break that rule.