Hi Nigel,
I'm afraid it was me who made the reference to Methuen in response to a colour query,which I hope would help point the questioner in somewhere like the right direction.I don't normally like to quote exact colour references as I've teetered close to the edge over colour matches in the past,preferring to take them as a guide now,but,I do do think they are a valuable source of information that can lead to a informed opinion on the whole question of correct colour matches.I've never actually seen in the flesh a Methuen book,and Jamo is correct,they were not readily availabe and costly.As an aside,I looked on Ebay UK,and there is a used copy for sale at the moment,starting price of £175.
Dave.