In reply to Flinticus:
I made it about 12 hours for the three, steady walking but no running - it's about a 30km round trip with 2000m ascent, lots of rough ground, some bogs, some scrambling, plenty of pathless sections...
It's a brilliant spring/summer day out if you like a real leg stretch, but equally now the light is on the wane it'd be a memorable mini backpacking round too, with an opportunity to camp in some very wild country