Minimizing sleep current


I’ve been playing with a SODAQ Explorer kit and have pretty much got my project finished. The last thing I’m struggling with is getting the board to go into a sufficiently deep sleep. I’ve followed the example linked to in this thread but using that example I still have a deep sleep current of 5mA which is clearly much higher than it should be.

I’m assuming there is some set of peripherals I need to put to sleep as well and wondered if anyone knows what I’ve missed?