It seems there is a "view online" option on their website, although a printed version is available for £35.It was last published in 2015, having been published for its last couple of years by Key Publishing, who acquired it from Ian Allan with other titles. Other attempts by trade press titles have also now disappeared. The nearest equivalent is Who's Who in the Bus & Coach Industry, published by Yandell Publishing, which continues. I don't know how accurate that its these days, having not seen one for some years.
What was the Little Red Book ?