I can't be sure, but would assume that the red book is "The Parish Councillor's Guide" that you already have and the yellow book is "Local Council Administration". The latter is very thorough and was originally written by Charles Arnold-Baker, who was a barrister, specialist in local council law. He was a major factor in building up the National Association of Local Councils. Since his death, the book has been kept up to date by Paul Clayden. It's an excellent guide to most aspects of local council law, although quite expensive to buy.