Any bill concerned with public policy and affecting the rights and duties of the whole population or all of a certain specified class (e.g. all married women). In the United Kingdom they may be bills introduced by government ministers, or private members' bills, introduced by back‐bench MPs. Most public bills are presented first in the House of Commons, although a minority start in the House of Lords. Devolution to the Scottish Parliament (1999) and the Northern Ireland Assembly (1998) means that many public bills within their territorial remit are purely the preserve of these institutions.
http://www.parliament.uk/business/bills_and_legislation.cfm UK Parliament site with list of public bills.