Waterproof Cycling Ruck sack / Rucksack / Back pack / Backpack / Backpacks

Been using my Banjo Bro's bag for the last 3-4 years and it's still holding up well. Completely waterproof.

I also like the fact it's just one big compartment so you can put tool bags in, big boxes that sort of thing. I could manage with a smaller bag but it's always the times when you want a bigger bag you don't have one.

Reasonably priced too.

where in UK you can buy one? Could find US site only.