A great deal of nonsense is written on TSR about Rankings.
Here are a few things that are worth thinking about:
1. League Tables are compiled using a whole of data that has no bearing on u/grad courses - like research funding and how many books a Professor in a totally different area published last year. Its actually pretty meaningless stuff and you really dont need to get hung up on it when applying for an u/grad course.
2. Universities go through 'fashions'. One considered the coolest one year isnt the next. Opinions on courses come and go. And ultimately, your degree result wont be dependent on 'the Uni', but on how much work you do.
3. Rankings will never tell you if you will enjoy the course, or if you are likely to get the required A levels, or if you'll be happy at that Uni. The two things that will help you choosing a Uni/course are 'reading the course description' in detail, and going on an Open Day.