Ian Brewerton Architecture

Possibly he can, and in many cases, especially for very small jobs, this may be satisfactory. However, you are paying for the drawings in the price for the works. And you need to satisfy yourself that the drawings have been prepared by someone competent to do this. Non Domestic projects are subject to the Construction (Design and Management) Regulations, which put a duty on the client to ensure that the designer is competent: see the "Safety" page.