Well said nose nowt. You clearly know more than your name suggests.
As a footnote the spectators are amazing. We have been lucky enough to have decent enough weather each year so the crowds have been plenty.
All those going for a specific time. I have done 5 of these and each time the course has measured close to 26.4. That's potentially another 1.5 minutes. I've gone through 2 garmin and a tom tom in that time. Just a warning.
The first year they built a fake wall at mile 20 near the powerstation. Needless to say it's not been seen again. The power starion is bleak but they do try. They ship spectators there to increase the numbers and put in a bit of entertainment. Frankly none of that matters cos I'm in so much pain then anyway!!!!!!