Taking a cursory look at the (current) prices in the area, Chelsea and similar areas look like you might find a single place or perhaps two at those prices, but it won't be terribly appealing - attempting to actually rent for £480/wk looks like it gets you a studio/1bed flat.
Edit: So essentially, £25k/yr will get you almost nothing in upscale areas, a hell of a lot in downscale areas.