May’s Brexit Plan Comes Just in Time for Supply Chains

British leader’s proposal to tie U.K. to EU rules heartens some businesses but upsets advocates of a decisive break

LONDON—At the Channel Tunnel terminal in Folkestone, southeast England, trains arrive every seven minutes carrying trucks packed with goods from across Europe, spilling vehicles directly onto motorways that lead to Britain’s industrial heartlands.

The 25-mile undersea link between Britain and mainland Europe is critical to supply chains spanning the continent that require goods to arrive at their final destination exactly when they are needed.

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