The story: I drove out of work to a retail estate to get lunch. I then drove back to work after lunch, and returned to the retail estate immediately after work to do my week's shopping. The car park in question is at the London Road Retail Park in Newbury, operated by Vehicle Control Services Ltd. Their camera system did not detect my car leaving at lunch (when it's busy), but did detect it when I left later in the day; I was issued a £60 fine for exceeding the allotted free parking time with a single four-hour stay.
My first thought was to contact the security department at my place of work for entry logs into the car park, but, as is usual with my luck, the camera system was under maintenance during that week. CCTV footage could also not be provided to me under company policy, so it looked like I was out of luck -- until I remembered that Google is constantly tracking my Nexus 6P's movement, and provides a timeline of users' locations for their perusal.
So, I fired up my laptop, took annotated screenshots of my Google Timeline for that particular day, and attached them to my appeal email. A little while later I received the below confirmation of my success:
Google's location timeline is certainly not infallible evidence -- it can actually be modified by the user. But if you've got nothing else, it's certainly worth a try. If you're a mobile worker who drives somewhat regularly, it might be worth checking to see if your Location History is turned on under the privacy menu within the Google settings app on both iOS and Android.