Appropriateness of prospective PhD supervisor reviewing scholarship application before submission I'm currently in the process of writing an application for a PhD scholarship at a British university. The school's system requires a CV (resumé) with attached cover letter, along with a few other documents.

My intended supervisor is someone I've already worked with for my MSc thesis, and he has said that he's willing to proof read and suggest changes for my cover letter, using his knowledge of the university's system and what the interview panels are generally looking for to help word it in such a way to tick the boxes that he anticipates the selection panel will be looking for.

He hasn't shown my cover letter to anyone who will actually be involved in the selection process, and he himself will not be involved in the process in any way, but a part of me is still concerned that such help might be giving me an unfair advantage over other applicants who don't have the same kind of relationship with their prospective supervisor. Is receiving this kind of help OK or not?
It is totally normal that somebody helps with applications.

This is true, for example, for applications for scholarships (where potential supervisors help) but also for applications for grants (where, e.g., many universities have specialized units to help applicants to formulate their proposals).

Regarding fairness: I do not think that this is the right question. Unless the rules for the scholarship do not state otherwise, you can use any help to prepare your application you can get (of course, cheating is not allowed - e.g. accepting help for an online language assessment by a native speaker would not be okay).