In thought the UK CAA was a regulatory body
The CAA is a Regulatory Body; it applies Regulation as defined in Law, the UK Aviation Act, the ANO and EU law. It is not empowered to make its own regulation any more than a policeman can however; it may be asked to provided technical input to the drafting of aviation legislation.
The latter assumes that it has the necessary technical expertise to do so. In recent years with cost cutting in place, the CAA's expertise has fallen to an all time low. It is not their job to tell people how to operate aeroplanes; only to ensure that they do so safely and in accordance with the current regulation. It has a little more autonomy when it comes to the issue of licences and approvals.