Bath Olivers are large, round, plain, floury tasting savoury biscuits and they can still be found in large Sainsbury's stores. They are ace with cheese and some medlar jelly or, as my DH tells me, pickled walnuts.
My mother worked as a cashier in the Co-op when I was young and brought home large, brown paper bagsful of broken biscuits, of which the pink wafers were the most prized.
I had forgotten all about Jamborees but loved them and, indeed any gooey or sweet or chocolatey or creamy biscuit. When I was little I couldn't see the point of plain biscuits like Rich Tea or Maries or even Butter Osbornes. Still can't really as, if you are going to waste a few calories on something that does you no good, you might as well be hung for a sheep as a lamb.
Modern biscuits just don't compete with the old 'uns. Except for Hobnobs and Chocolate Hobnobs which are epic!
I eat two plain McVities Digestives for my breakfast with good Kenyan coffee every day and count my blessings.