"...the author of the Regulations has been able to designate that, within a particular zone, some uses are clearly permitted and some are clearly prohibited. In between, there is a whole range of uses which are thought not to be capable of such clear-cut demarcation. It is, therefore, left to the appropriate planning authority to determine in each particular case whether such use will, or will not, be permitted. That calls upon the planning authority to examine each application upon its merits, and to apply the relevant planning criteria in the exercise of its judgment and discretion. In that context, to say that the applicant cannot go ahead unless he gets consent is to say no more than that he can go ahead if he does get consent, and the form of words chosen by the draftsman is a mere matter of drafting preference. To hold otherwise, and to place some prima facie prohibition upon a consent use, is likely to deflect the planning authority from its duty to examine each application upon its merits, and from a neutral base."