Photos of the grey butcherbird on Google Images have some as being a sort of charcoaly dark grey-black, while other photos are similar to mine. The bird I saw definitely looked brown-ish as it appears in my uploaded photo.
I'd agree with grey butcher-bird. This could just be a young one. They're quite common but a bad sign if you enjoy having other birdlife around. They're really aggressive and will chase a lot of the smaller birds away.
I never bought the app. I only had the free, lite version. My field guide is good only when I have a general idea where to start. Besides, who needs an app or a field guide when I have you guys who enjoy identifying birds?