I wasn't a reporter for very long, thankfully, since I wasn't very good at it but I've worked with a few people who really were. What they all had in common was being highly organised, obsessive about reading every document they could get their hands on, tenacious in following up leads and good at building rapport with useful contacts.
These are not skills that are necessarily valued in modern journalism, which focusses increasingly on commentary rather than on story-getting. Investigative journalism is viewed as taking up a great deal of time and resource to produce stories that don't necessarily interest that many people and can end up getting you sued. Just about the only place that it is practised on a regular basis is in the pages of Private Eye (which most people buy anyway for the humour and gossip).
So well done Andrew Marr, who today announced that he is to launch an award for those tenacious reporters who obsessively dig out stories and break exclusives (as opposed to getting them handed on a plate through buy-ups). He is considering naming it after the late Anthony Bevins, political editor of the Independent and then the Express. I worked on the same paper as Tony for a while, though I didn't know him at all well, and he was legendary for his skill at uncovering political scandal by methodically working through the documents (reports, answers to parliamentary questions) that others wouldn't bother to read. (He was also the only journalist to leave the Express on point of principle, without another job to go to, after it was taken over by Richard Desmond.)