Two songwriters (P), members of the English pop group Fleetwood Mac, signed a publishing agreement with a music publisher (D) on a standard printed form. Under the agreement, P assigned to D the copyright throughout the world of all their compositions for a period of five years. P agreed to deliver to D a minimum of one complete musical composition per monthand D agreed to promote P's compositions to the fullest. However, D gave no positive undertaking to publish any of their works. The pop group split up and P commenced work under a new management. The group, now working in the United States, has recorded a new album of P's music. The original publisher, D, seeks to restrain the sale of the new album in the United Kingdom.

Discuss the legal enforcement of the original agreement?