One trick we used for this beer was to make our own brown malt. Using the guidelines from the "All Things Homebrewing" blog, we got really close to real brown malt (we had a reference sample on hand), although ours seemed to be a bit more aromatic, doubtless because of the fact it was freshly toasted.
Old Toasty
Northern English Brown ale
5.5 gal batch, brewed 9/5/10
9 lbs Maris Otter
1 lb Crystal 60
1 lb homemade brown malt (made from Maris Otter)
0.5 lb Pale chocolate malt
1 oz Northern Brewer (8.1% aa) 60 min
1 oz Northern Brewer 20 min
1 oz East Kent Goldings (5% aa) 3 min
1.055 OG
1.017 FG
5.0% abv
45 IBUs
Yeast propagation: Wyeast 1968, used 3/4 cup slurry from previous batch (a bitter)
Water profile: "Mosher's Ideal Mild ale" (Ca++ 83 ppm, Mg++ 12 ppm, Cl- 92 ppm, SO4 112 ppm, Na+ 38 ppm, carbonate 106 ppm)
Single infusion mash at 156.5 F
Cast out 5.5 gal, 71% brewhouse efficiency
Fermented at approx 69 F
9/5 Brewed
9/11 at 1.020, got roused a bit
9/19 at 1.017. Bottled to 1.9 vols CO2
Review (10/23, about a month in the bottle)
Aroma - Toasty, light chocolate, light roasted. A little sour tang, almost like sourdough.
Appearance - Deep chestnut brown, ok clarity (not great), head small but retains, no lacing.
Flavor - Toasty malts, chocolate, hint of smoke almost. Robust malty body, some caramel sweetness. I'd say the malt bill is about perfect for what we were going for. Lasting bitterness which may be out of style, but is enjoyable.
Mouthfeel - Most of these bottles got overcarbonated, and I'm not totally sure how or why. I knocked out some of the carbonation in this sample by first pouring it vigorously into a pyrex glass. When the carbonation is knocked-out a bit, the mouthfeel is full and rich. Great.
Overall - When properly carbonated, this beer is awesome. Robust and satisfying but still very much a brown ale. Could reduce the IBUs to around 35 and maybe take the pale chocolate down to about 0.4 lbs. A little diacetyl might be nice in this beer, possibly try a different yeast strain (1084?).