At maturity, a typical British male will be about 12 to 18 pounds, with the females somewhat smaller. It does take this breed a long time to mature. Both sexes will continue to fill out and thicken up until 4 years of age. Each sex has its own set of characteristics. Males tend to be more happy go lucky, and are less picky about who they receive attention from.
Females are very loyal to a smaller number of people and are a bit more serious.
Females are quicker and I think they are smarter then the males. Some of this may be breed personality. Some may be that with their dense coat, they get over-heated sitting on us warm humans. A British likes to be around you and by you. They will follow you, watch you and basically supervise all aspects of life in their house.