Probably just some incorrect geolocation data stored on your computer. Or perhaps some application set up for or mis-configured to use German.
Start here:
Type "WIN + I" and then select "Region & Language". Any References to German.
Verify that your Date & Time settings are correct for UK.
In Firefox type: "about
references#content" (without quotes). Look for any German listings.
I sometimes see false location indications. I.e., "nearby locations" are somewhere across the country.
Generally attribute that to desperate marketing attempts to gather any information they can about me by harvesting any available and accessible bit of data they can from my computer.....
So, if you did something as innocent as lookin up a German city or beer then your computer may have some "I am German" flag or indicator set.