Kenneth Martin was for me one of the grand old masters of Constructivism. Outside England hardly known, but considered by many of great influence and importance. His best works for me are his prints in which he excels. His wife Mary was a gifted artist too and from both www.ftn-books.com has some nice publications. I only know of one exhibition outside Great Britain, which is the Bottrop exhibition but when you see one announced , i strongly recommend a visit to discover yourself the importance of Kenneth Martin.