Because you may find as I did a few days ago, that funny noise was the early stages of the Clutch Release Thrust Bearing ... breaking up ... 
They can go on for many thousands of miles making that noise, or self destruct next day as happened on this occasion....
Hey ho ... another job for me old bones... just what I needed ..
Voila :~
I never realised the simple Clutch Release Bearing was composed of so many parts .. some of its balls are missing ...
Here's pictures of the old and new Clutch Assemblies :~
There's a happy ending ... car is running beautifully now... praise be.
..
They can go on for many thousands of miles making that noise, or self destruct next day as happened on this occasion....
Hey ho ... another job for me old bones... just what I needed ..
Voila :~

I never realised the simple Clutch Release Bearing was composed of so many parts .. some of its balls are missing ...

Here's pictures of the old and new Clutch Assemblies :~

There's a happy ending ... car is running beautifully now... praise be.
..