After Brexit, the United Kingdom is unlikely to continue pursuing integration with other Member States of the European Union, including through competition policy. As a result, the time is ripe to reconsider the role of the single market imperative in competition law, in particular in relation to vertical restraints where the goal of market integration plays a pivotal role. This article shows that recent European vertical restraints decisions and case law, in particular concerning territorial and online restraints, have been motivated in whole or in part by the single market imperative (SMI). It then examines how the law in the UK might follow a different path post-Brexit, taking the Ping case as an example. However, a similar change is not likely to be forthcoming in relation to the law governing pricing restraints, which are not obviously linked to the SMI and which have been the subject of much enforcement in the UK both before and during the UK's membership of the EU.