Hi Malcolm, it might be possible to enable it anyway, but I'm not sure it will work properly. If you want to try it, here's how you would do it. Please note that this is not officially supported outside the U.S., which may be for privacy/legal reasons. (1) In a new tab, type or paste '''about:config''' in the address bar and press Enter/Return. Click the button accepting the risk. ([[Configuration Editor for Firefox]]) (2) In the search box in the page, type or paste '''extensions.formautofill''' and pause while the list is filtered ''Firefox should display numerous preferences.'' (3) Double-click the '''extensions.formautofill.available''' preference to display an editing field, and change the value from '''detect''' to '''on''' then press Enter or click the blue check mark button to save the change. After this, you could try loading or reloading the Preferences page to see whether the relevant section is now available so you can manage this feature. Either: * Mac: "3-bar" menu button (or Firefox menu) > Preferences * Linux: "3-bar" menu button (or Edit menu) > Preferences * Windows: "3-bar" menu button (or Tools menu) > Settings (previously "Options") * Any system: type or paste '''about:preferences''' into the address bar and press Enter/Return to load it In the search box at the top of the page, type ''autofill'' and Firefox should filter to the relevant section: <img src="https://user-media-prod-cdn.itsre-sumo.mozilla.net/uploads/images/2021-10-12-16-23-22-1d3f08.png"> Any luck?

Oh, if the built-in feature doesn't work with U.K. addresses, maybe there's an add-on that can do it?