H J Blackham was an amazing man and my obituary of him appears in today’s Guardian on page 34 – it is now available online.
Other obituaries have appeared in The Independent and The Times and if you’ve never read any of HJB’s books you should definitely try him and there’s a good anthology available from the BHA.
Of course, his greatest monuments are the organisations he founded: the British Humanist Association, the International Humanist and Ethical Union and the Journal of Moral Education amongst others.