Some women gained a reputation for brewing the best ales, and would sell it from their homes. They built extra rooms and pubs were born. When a beer was ready to be drunk, the 'ale-wife' would put a stake covered with evergreens outside the house to let the neighbourhood know there was fresh beer available. These ale stakes can still be seen in the form of patterns and moldings on some pubs and breweries.
Pub names have a colourful history too.
In Roman times pubs would also change money and were known as the Chequers. The Green Man referred to a pagan beast who covered himself in greenery before attacking villagers. Many names refer to the heraldic arms of a respected nobleman, eg the Red Lion or the Eagle and Child. Inns were often used as meeting places for trade associations and would sometimes bear their crests, hence names like the Farriers Arms. Hope this helps.