Could any one explain LAB mode to me and its advantages for retouching/restoration?

Many thanks

Hi Toriat and welcome to Retouch Pro. Its hard to give a short answer to that question, but a book by Dan Margulis "Photoshop Lab Color" goes into Lab color in detail. If you are comfortable with RGB color space in photoshop then perhaps you may want to look at Lab Mode Color space.

Thanks very much, I'll look in to that :)

Lab is more suited to color correction, removing moiré's, sharpening/noise moves than Retouching an image. Not that it can't be used for it, but it is not ideal.

Chris