Boris Johnson heads to the north of England later, after the Tories' biggest election win since 1987.
Boris Johnson tells Nicola Sturgeon in a phone call that he has "unwavering commitment" to the union despite the SNP's election success.
The Labour leader says he will not walk away from the role until a successor is chosen.
She says she is "proud" to have been the Liberal Democrats' first female leader, as she steps down.
New rail timetables come in on Sunday, with more and speedier services promised on some routes.