We went down to the Black Bull in Sawston yesterday. Went down on the bus, specially for their 1st Annual Beer Festival.
We weren't disappointed. A decent range of excellent beers, all the ones I tried were very good, and a small barbecue and hog roast (although we had some of the bar snacks as we were getting a bit peckish).
Staff were very friendly, and there was a very good atmosphere, so highly recommended.