Webmasters who do business in the USA or sell to people in the states fall into a special needs class of Google users. You may be trying to monitor ad campaigns or keep tabs on competitors there who are not listed in your local google.co.uk serps (or google.de or any of the other local google results pools). You may live in New York state but be in Belgrade or London today, maybe visiting Mumbai - where your default Google search option in FireFox will redirect you to their google.in.com results. Unfortunately, the default behavior of the FireFox Google search option will redirect you to their results wherever you may be that day. They don't ask whether that's where you wanted to search and often it changes the language you see for the results.
You could always bookmark the google.com/ncr URL to visit the US/English results but I found that you can add it to your search preferences to use the same as any other search option with FireFox browser. It is called Always .com Google: [
addons.mozilla.org...] and installed as an add-on. It works the same as any other search option. You can use it in the browser search bar or in the context menu. Type in what you want to find in US google.com results, select the always .com Google from the search options dropdown and voila! US search results, the same as you'd see at home.
There are options to see suggestions, to select their search as a Home Page and other settings. If you've ever run into that situation, there is an answer - at least in FireFox.
To view or change search options in FireFox, you use the FF Menu Bar to select "Preferences" then select "Search" and it will show you the search options you have installed. At the bottom of that list there is a link to "Find More Search Engines" and visiting that link shows 3,582 results that you can sort by several parameters. It took me a while to find this one so I included that link.