Using Brown Malt

For a brown ale, and an English Mild, can Brown malt simply be substituted for pale, or should it be used in combination with pale? For example, Orfy's mild: how would brown malt work in something like and in what capacity?
Thanks!

You'll want to use it as a specialty grain with the bulk being pale malt, as brown malt has no diastatic power. I'd recommend 5-10% of the grist, depending on how many other specialty grains you are throwing in there. A little goes a long way.

I thought brown used to be what was used for brown ales way back in the day. I guess a protein rest was utalized?

IMO Brown malt is sort of a misnomer in that it makes you instantly think of a brown ale, but I feel it needs to be used with restraint.
I used a 3/4# of it in a mild recipe. I was almost unexpectedly, too much, it gave the final product a really heavy nutty flavor almost hazelnut coffee-ish flavor. I didn't mind the flavor but I was really going for a mild background flavor. It was more pronounced in nut flavor than a Goose Island HexNut or Rogue Hazelnut Brown.
It was only 9.25% of the grain bill, So I would suggest caution in using it in large ammounts unless you were going for a really nutty flavor.