In the previous Firefox, I could bring up a list of pages viewed within a tab, so could quickly jump back several pages, but I can't find this now.

You can get the drop down list by either right-clicking on the back/forward buttons, or holding down the left button until the list appears. If you want the drop-down arrow you can add it with the Back/forward dropmarker add-on - https://addons.mozilla.org/firefox/addon/backforward-dropmarker