It looks like Boris Johnson is cranking up his leadership challenge and it is hard to fault his timing, even if one questions his motives. The widely-shared pivotal assumption that the heads of EU governments will readily concede access to the Single Market looks to be on the point of being rumbled. Some people may still be believers while many are no longer sure but it seems that those closest to the negotiations know the game is up. Mr Johnson must have decided that before the grim truth is revealed now is the time to step forward as the leader of those who wish to leave the EU whatever the cost. In order to escape any blame he needs to leave the government, preferably by being sacked (he could earn a lot more as a journalist), and more in sorrow than anger run for the leadership just as Mrs May is seen to be making more and more concessions. For him to be kept off the final ballot of Party members Tory MPs would struggle to rank two candidates above him. He could well triumph as the party members who support Brexit probably outnumber those who share many MPs’ view of him as self-serving and unreliable. Once in Downing Street, Mr Johnson would be able to challenge rebellious Remainers to back him or risk an election for which they could be deselected as Tory candidates and Labour could win. Judging by his latest outbursts, he neither understands nor cares about the economic consequences of a rupture with the rest of the EU but intends to blame everyone else for anything that goes wrong. Mr Johnson may even fancy his chances in a general election through targeting Brexit voters and also those who fear old-fashioned Socialism. However, Labour has its own core vote of public sector employees and the anti-austerity tide (which Mr Johnson also wants to surf) is running strongly in its favour, especially amongst younger voters (Figure 2). A Johnson vs. Corbyn contest could well result in another hung parliament and a minority government that would prefer to accept the EU’s terms than be held responsible for the likely alternative of economic and legal chaos. What is not clear is how investors will cope with so much further uncertainty and the prospect of a Labour government. UK equity prices currently reflect moderate overall pessimism interspersed with rallies on sterling weakness, thereby offering both upside and downside.