David Ward is the principal author of the OPAL event display program. He also gave me considerable help in the technical details of producing the pictures of OPAL events and feynman diagrams. Some of the feynman diagrams I stole directly from David's web pages on LEP1 and LEP2 physics with OPAL.
Nigel Watson gave me help with the OPAL event display program and with a number of thorny problems.
In addition to putting up with my day to day technical incompetence, Andrew McNabb suggested an excellent way of generating the 150 or so .html files associated with the challenge questions and answers from just two template files.