This chapter considers the challenges faced by Pym’s whipping operation on the European issue, including resource limitations in the face of persistent anti-Marketeer dissent. It particularly focuses on the crucial relationship between the Prime Minister and Chief Whip, highlighting the apparent tensions over strategy and approach. It is arguable that the parliamentary battle for entry into Europe was successful due to the skilful whipping operation, and despite the Prime Minister’s scepticism over his Chief Whip’s approach to party management: Heath was notably reluctant to accede to Pym’s critical advice to hold a free vote on the principle of entry, and impatient with Pym’s methods of party management. However, the passage of the EC Bill, paving the way for UK accession, was secured due to a combination of efficient organisation and a generally tolerant approach to whipping, especially in relation to the diehard anti-Marketeers. This approach was both principled and pragmatic; it reflected a hard-headed realism that proved instrumental in maintaining good relations with prominent anti-Marketeer dissenters, ensuring accurate intelligence gathering and enabling effective targeting of more amenable or loyalist anti-Marketeer dissenters. This chapter concludes by arguing that, in the absence of specified and consistent use of referendums, the tolerant principles and approach of loyal dissent should operate as a whipping convention on issues of such fundamental constitutional significance as European integration.