All the Jaguar cars of the period had Radio Codes. All the cars from NEW had a card (actually a PAIR of cards) with the code in the owners manual.
The North American market radio head units normally did not require the code unless some parameter was changed like 'country/market frequency' or other feature that altered the settings.
I don't remember all the settings that will trigger the required head unit code.
The button 1 (country/frequency) will definitely need the code but the AF (alternate frequency) might not or the RBDS enable might trigger the need for the code?
When I did PDI on new cars I used to know all these things but the list escapes me now.

 

Interestingly enough, my 2000 required a code entry at the beginning of our relationship, but for some reason after 10 years or so after connection and disconnecting for various reason, it gave up and just said, I'm not doing that anymore. LOL
They say the car learns how you operate, well, there you go.

 

If you have the code, just check the settings to make sure the head unit is set to US.

 

This is definitely a case of overthinking. Remove the battery, take it home, keep it charged, refit when needed, reset windows, drive away.