The battle for the future of Scotland has begun after a dramatic set of British election results left the U.K. starkly divided.

Prime Minister Boris Johnson’s Conservative party cemented its grip on Labour’s former heartlands in northern England, while in Scotland parties pushing to split away from the U.K. won a historic majority.

That threw Johnson and Scottish National Party leader Nicola Sturgeon into what could be a vicious and lengthy showdown over whether a new referendum should be held over Scottish independence.