Neither. There is no requirement to keep a record of who is driving your car at all times. On a long trip it is entirely possible that one of two (or more) people could have been driving at any particular point. These two or more people may, or may not, include the registered keeper.
Why then, should the registered keeper be fined because the two (or more) people he lent the car two cannot remember who was driving?
Er, you seem to be missing the point. Given that we are discussing convicting innocent people, there is no requirement that you actually commit an offense for it to "happen to you".
If you were to, legally, lend your car to someone and their friend to drive 800 miles it would be natural to expect them to share the driving. If they can't remember who was driving 14 days later when the NIP arrives (on YOUR doorstep), what do you do?
There is no proof that anyone committed an offense. Given the photo, someone (the driver, at that time) committed an offense. There is no proof of who the driver was. There is NO CASE.
-- David Taylor "The future just ain't what it used to be."
