From Bairds UK
Colour 110 ebc
Brown malt has a dry toasty malt flavour. Until about 1800, stouts and porters were usually made with a grist of 100% brown malt. The development and adoption of the hydrometer along with the development of black roasted malt, aka black patent malt, brought about changes in grain bills.
In 19th century stouts brown malt was used in conjunction with amber, pale and black malts eg Triple Stout (aka Russian Imperial Stout) grain bill
Small amounts, 1 or 2 per cent, can be used in English bitters and other pale ale styles for seasoning and to add depth of colour. Increasing amounts up to 15% are used in amber and brown ales, especially where the dryness of this malt is used to balance the sweetness of higher proportions of crystal malts.
Contemporary porters benefit from the generous use of this malt, say up to 25% depending on the rest of the grain bill.