If the Modern British Posters book and exhibition appealed to you, here's another book focusing on the topic, Art for All: British Posters for Transport.
As the title makes implies, the emphasis here is on posters designed for London Underground and the railways, dating from 1908 when the publicity programme was started by London Underground. Its 208 pages feature many well known poster works, it also examines great examples of the work of McKnight Kauffer in more detail.
Offering a great overview of the topic, the book accompanies an exhibition at the Yale Center for British Art in America and uses work from their collection, alongside images from the London Transport Museum and National Railway Museum in York.
Buy it for £23.77 from Amazon