Posted by Neil Wyatt on 27/05/2016 14:12:48:
In Firefox the route I gave above clears the cache without losing the history, so I'd recommend it over the method given in that link.
The method in the link that Katy gave is actually fine for my Firefox. It pops up the "Clear All History" box but only the "Cache" is checked. "Browser History" (and everything else) is unchecked. And when I used it, my browser history was indeed retained.