The only major difference is the OG. Through trial & error I stumbled onto this recipe. I use it to brew my 60, 70 and 80 shilling beers and the only thing I vary is the amounts to hit the OGs I want.
1% chocolate malt
1% brown malt
0.5% peat smoked malt
15% munich
20% medium to dark crystal
62.5% pale 2 row
Shoot for 15-20 IBU from a single bittering addition no matter whether you're trying for a 60, 70 or 80 shilling.
...And the most important part: either wyeast 1728 or WLP028.
I've also discovered that if I omit the peat smoked malt and increase the brown malt to 4% at the expense of the crystal that this produces a killer brown porter. The IBUs have to be scaled up to about 25 IBU too.
Cheers! :beer: