Apart from his Private Papers, which can be found in profusion second-hand, it appears to be a field of one: A Little Chit of a Fellow UK History http://www.liberalhistory.org.uk/uploads/63_Lippiatt_Grimwood_A_little_chit_of_a_fellow_review.pdf
Many thanks Vitesse, I've had an interest in him for quite a while and been tearing through Hansard so will pick those up.
What in particular are you interested in? I have a fairly sound knowledge of most of the literature about H-B, including both books mentioned. Best, Alan
