Whilst there is an "open in blueocean" link from the calssic UI to blue ocean there is no corresponding button to go to the classic UI.

THis may have been a design descision but it is fundementally important to be able to drop back to the corresponding classic page as blue ocean is not functionally equivallent.

e.g.
No support for trend graphs
Lack of integration with many plugins (e.g. cucumber)
Console log is not updated live (related bug the current console link is uneabled)

As an admin and power user of an instance if users kept sending me blue ocean links to jobs nested deep in folders I would end up removing the plugin as it is too time consuming to get to the actual corresponding page that it would actually annoy me.

Therefore until the UI has enough functionality to prevent power users to have to do this there needs to be an easy way to get back to the corresponding classic page.