If there are only three or four parties, prepare for a TV panel debate, where the party leaders will be invited to participate; otherwise, ask each party to prepare a party political broadcast (2-minute length) to be recorded in the studio. (WebCorp)
Second, groups with extreme political opinions may present candidates who have no hope of winning, but who ensure that their party has the entitlement to a free party politicl broadcast that is given in Britain to any party with at least fifty candidates. (WebCorp)
He explained that the BBC was not required to broadcast party political broadcasts or election broadcasts by statute but "because time on television is offered to political parties by the BBC for them to explain their policies and politics as they see fit." (WebCorp)