This from the wikipedia article:
- Alcohol Content: 5.7% by volume
- Beginning Gravity: 14.5 Plato
- Ending Gravity: 3.8 Plato
- Bitterness Units: 40
- Yeast: Top-fermenting Ale Yeast
- Bittering Hops: Goldings
- Finishing Hops: Willamette
- Malts: Two-row Pale, Munich, Chocolate & Caramel
Palmer’s recipe:
http://ericsbeerpage.com/Beer/Recipe/snp.html
My recipe:
Ingredients: (for 23L)
Malts
3.25kg of Pale Malt Extract (syrup)
275g of Chocolate Malt
275g of Crystal 60L Malt
200g of Munich Malt
100g of Black Patent Malt
Hops
65g Goldings (5%) at 60 minutes
25g of Willamette (5%) at 40 minutes
15g of Willamette (5%) at 20 minutes
Yeast: American Ale (1056)
BG for 3 Gallons 1.079
OG for 5 Gallons 1.048
Total IBUs 39
chris.:
For specialty grains I like –
150-200g each of dark crystal (cara aroma) & standard crystal.
150g of pale choc
50g of roast (carafa special).
400g of brown malt
750g of munich
lethaldog:
4.5kg ale malt
400 gm crystal
400 gm dark munich
300 gm choc
50 gms roasted
60 gm E.K.G ( 60 mins)
20 gm E.K.G ( 30 mins)
1/2 teaspoon irish moss
Wyeast irish ale ( 1 litre starter)
Mashed for 60 mins at 68*C and fly sparged ( mash 14 litres) ( sparge 18 litres)
Boiled for 60 mins yada yada yada and chilled, pitched yeast and you know the rest 
