I just remembered I had to ask this. It's a dumbass question so I'm sorry in advance, anyway the rear wiper washer doesn't work at the moment, it worked last week, just not now - when I need it.
I'm assuming the rear and front washers is supplied by the same reservoir, yes?
If so I think I may have a blockage - this is where the dumbass bit comes in - I can't find the rear jets, are they hidden away in a pain in the arse place to get to. Or, this being far more likely, am I being a and I just can't see them?

They are part of the wiper arm, two small holes near the pivot.

I had mine unblocked last week at the dealers, the also cleaned out a one way valve in the pipe work and charged my £20 for the privilege.

Are you sure yours is not frozen? 
Gone - Range Rover Supercharged 2006

They tend to freeze very easily and the pressure isnt great so it tends not to push the ice out of the nozzle. Also if you run without a winter mix of antifreeze in the washer the one way valve gets damaged from the ice expanding in it and can top letting water though in either direction. 

And don't confuse coolant antifreeze with screen wash antifreeze as thats likely to bung-up the entire system or worst still damage your paint work! 
Gone - Range Rover Supercharged 2006