I've not been hands-on with it yet, but the Soulvation (aka Northern Soul Stories) book by Neil Rushton certainly sounds interesting.
According to the write-up, its a collection of 'I was there' quotes from the soul singers who made the tunes and the working class kids who bought it, from the early roots of the 60s club scene to the scene's height at places like the Wigan Casino, Blackpool Mecca, The Torch and The Catacombs, finishing with Northern's latter day renaissance.
256 pages in full colour with illustrations, you can pick up a limited edition (500) hardback with an exclusive 7-inch of Jackie Ross' 'Trust In Me' b/w 'Lucky Lucky Me' by Marvin Gaye for £29.99 or a softback for £19.99. See sample pages and find out more at the website