I first met Arnold in 2001 or 2002 when undertaking the MSc Archaeological Prospection course.  I remember we were surveying in his back garden with the Pulseekko 1000.  At some point, when it came to choosing dissertation topics I must have expressed some kind of interest in earth resistance survey because I ended up working closely with Arnold on a project about the square array.  Once my disseratation was done, he was of course insistent that we should publish the work, while I dragged my feet!  Over 10 years later, I still get quite excited about the square array and about ERT.  I think I have Arnold to thank for that!
More recently I have been looking into the history of archaeological geophysics in Orkney which reads like a whos who of Arnold’s former students.  I wasn’t surprised at all to find Arnold himself, where else, but right at the beginning of the story.