The heritage railways, tired of BR frequently upping the charge by a penny, BR had long since given up using priced stamps or labels, sought changes. A new agreement between the Post Office, the Association of Minor Railways, British Rail and Northern Ireland Railways became effective on 3 June 1974. The agreement allowed the minor railways (Association of Independent Railways Ltd) to fix a fee independently of BR. Under the agreement, BR also benefited since it was no longer required to accept letters from a minor railway without the payment of an additional fee. Changing commercial circumstances caused BR to withdraw completely from this nationwide service on 8 June 1984. The Ffestiniog Railway and other heritage railways continued to offer this service. At the insistence of the Royal Mail, a new agreement, a separate contract between the Royal Mail and each participating heritage railway company, was introduced on 18 December 1998.