Just something I forgot to add yesterday. I recently bought a copy of 'A Walk Through Time' which is the definitive history of the Parish Walk and was written by Dermot O'Toole, who has finished the course on numerous occasions.
It's a great read and covers everything from the historical origins of the walk to a year-by-year report. I'd recommend having a skeet at it in the bookshops at the very least. I think it's available pretty much everywhere.
By the way if anyone found a yellow Dunlop hat down at Ronaldsway on Sunday, I would be very gratful as quite amusingly it blew off my head in the middle of the walk.