If you are using Windows Vista it is unlikely that you're using the latest version of iTunes, because the latest version (12.11.3.17) cannot be used by Windows 7, so I doubt very much that it can be used on Vista.
Uk_Help wrote:
I am running the latest version of iTunes on both (I think)
If you mean "both" on your computer and on your phone, the phone does not have iTunes installed on it. The phone uses iOS.
However, although your phone may have originally had iOS 7.0 on it, which I'm guessing could be used on a Windows Vista machine, if messages on the phone tell you that the software is up to date, and you have updated the phone over Wi-Fi (that means not using iTunes) then I think you will find that at the time of writing, your phone is iOS 12.5.4, which is almost certainly why the phone now requires a newer version of iTunes than you have on your machine. Check the phone's software version in Settings/General/About>Software Version.
You can check iTunes' software version by clicking on Help/About iTunes. I think it may be 12.1.3
Don't forget, Apple has a habit of telling you that a device's software is "up to date", when what it actually means is that it is running the latest version of software for that particular product. A subtle, but important difference.