Older versions of Firefox can be found https://ftp.mozilla.org/pub/mozilla.o.../24.8.1esr/

Thank you for your response, but that is not clear at all and when I click on them there is no option to download?

It is clear as you just pick the OS and then the Language then the Firefox Setup 24.8.1esr.exe

Since you use Windows and likely en-US here it is https://ftp.mozilla.org/pub/mozilla.org/firefox/releases/24.8.1esr/win32/en-US/Firefox%20Setup%2024.8.1esr.exe

Do note that the old Firefox 24 ESR is no longer supported with security and allowed stability fixes as the 24.8.1esr came out in September. There was no 24.9.0esr when 33.0 and 31.2.0esr was Released.

https://www.mozilla.org/security/known-vulnerabilities/firefoxESR.html

Thank you for helping me james.

I can't be seeing what you're seeing because it wasn't clear to me at all! I've downloaded many browsers.

Re: "Do note that the old Firefox 24 ESR is no longer supported with security and allowed stability fixes as the 24.8.1esr came out in September."

I appreciate what you are saying, but I cannot use what I have at the moment. My computer is repeatedly locking up.....Firefox has crashed a number of times today, I didn't have a problem at all with 24.8.1.

I am en-UK, can I change that?

That would be en-GB rather. https://ftp.mozilla.org/pub/mozilla.org/firefox/releases/24.8.1esr/win32/en-GB/Firefox%20Setup%2024.8.1esr.exe

Thank you very much.

I just studied it again and found Win32...clicked on there and can see now. :)

I had exactly the same problem when the standard Firefox updated to 28.0, I was advised here to use ESR.