As long as Corbyn remains Labour leader then clearly he has a good chance of becoming, at some stage, prime minister. The above active betting market is not about that but who is going to step into Theresa May shoes when she stands aside.
Probably the most significant political news affecting this market over the past week has been the statement by her that she will not fight the next general election as Conservative leader. That means that it is highly likely there will be another head of the Tory Party before the next general election who would look set to become PM.
TMay’s statement has virtually blocked off the the possibility of Corbyn becoming as a result of him leading his party to victory in the next general election.
If he remains Labour leader then he clearly has a chance to become Prime Minister after the next general election but Theresa May’s announcement means that it will be her successor as Conservative leader that he would be replacing.