Sue, I have a web site started, which is intended to research the industrial output of Chance & Pilkington - very much work in progress! I already have access to four boxes of samples, all of which contain different samples, clear and coloured but these might have different labels. A really great find!www.chance-pilkington.co.uk
The output from both companies were mirrored, particularly after 1953, so many of the trade names were duplicated, although there will be differences in the glass manufacture.
Frank's suggestion to try scanning them is a good one - I have had good success with this, although a little tweak in image editing software should be all that's required. I can always help here, if required.
EDIT - Anne: perhaps one for industrial glass?