Hi Max, the breeds currently banned in the UK under the Dangerous Dogs Act 1991 section 1 are the Pit Bull Terrier, the Japanese Tosa, the Dogo Argentino and the Fila Braziliero. It is also important to remember that the Act also applies to breeds considered to be of pit bull type, which includes American Staffs. More information on this can be found
here, particularly if you read the pdf leaflet. Hope that helps :)
-Kay