Great Kevin, thanks! hadn't spotted the manuals down there at the bottom of the page. I was looking in the top section where the software downloads are.
One query remains: Is there a combined 'What's New?' type document that details all of the changes from the 'June 2011 edition' hardcopy manual to the current 1.5 pdf manual? I like the hardcopy manual, I find it convenient to have it sitting alongside when I'm using Spark, but I wanted to mark in it where there have been updates, additions, and changes, without having to laboriously compare the new pdf and old paper manual side by side.