WORCESTER, ENGLAND - MAY 16: Boris Johnson MParrives in Stafford to board the Vote Leave, Brexit Battle Bus on May 17, 20016 in Stafford, England. Boris Johnson and the Vote Leave campaign are touring the UK in their Brexit Battle Bus. The campaign is hoping to persuade voters to back leaving the European Union in the Referendum on the 23rd June 2016. (Photo by Christopher Furlong/Getty Images)