Part of the problem with British tennis is that the game is corrupt. Winners and losers are sorted out in the changing rooms before a match. That means that we never stand much chance at getting truly world class players coming through.
By world standards, Murray is a good player and did well to get to the final, there's no point saying otherwise. Will he ever win a grand slam? I don't know, but I'd guess not. We'll just have to wait and see who is next to pay their way through to the top of the British rankings.
It's coincdence that Murray is the person commenting in this article. It's just the first link that cropped up. click here
There's not a whole lot of detail in the article, but makes the point.
At lower levels, games do not have one umpire per court. Typically, there's one 'roving' umpire covering half a dozen games. A lot of the time the umpire is a relative of one of the players. This leaves the players to score and referee their own games for the majority of the time. The opportunities for match fixing are there, and are used.