Lowe Pro Flipside 200 backpack. Comes with all the usual movable inserts etc.
It's particular selling point is the security of it's opening from the back panel so you can't have stuff nicked out of it without removing it from your person.
However, I think it's USP is that it's the best bike riding backpack they make as it's slimmer like a camelback and not as bulky and wide/ squat as the Trekker range, so ideal for the PoTM crowd.
However, I just don't ned it. In fcat IIRC, I have never used it.
As I never quite did ride to shoots, preferring to drive.