At the front of my garden I have a very low wall, topped with concrete
copin slabs. These have become very discoloured, taking on a pinkish hue. I have tried cleaning them with a cleaner but am still not happy with them. Does anyone know if they will paint OK and if yes what sort of paint should I use?

The staff at B&Q might know.

In fact you could ask.
http://www.diy.com/customer-support/con ... cs_contact
Scroll down for 'general enquiries'.
There are also guides of the website, which I didn't look at as I don't think all that many people paint concrete coping slabs!

No idea where you would get it in the UK but you can get concrete paint much the same as you paint rendered houses you can paint concrete.

My rendered house is painted with Sandtex