names
Prominent figures can just be named in stories, with their function at second mention: "George Osborne said last night ... " (first mention); "the chancellor added ... " (subsequent mentions)
Where it is thought necessary to explain who someone is, write "David Weir, the Sheffield United manager, said" or "the Sheffield United manager, David Weir, said", etc.
In such cases the commas around the name indicate there is only one person in the position, so write "the Tory leader, David Cameron, said" (only one person in the job), but "the former Tory leader Michael Howard said" (there have been many).
Do not leave out the definite article in such constructions as "style guru David Marsh said ... " It should be "The style guru David Marsh" (if there are other style gurus) or "David Marsh, the style guru, ... " (if you feel only one person merits such a description)