You probably should have obscured his number plate to avoid hassle. Data protection act and all that.
McBryce.
Only really a concern for corporate entities making collections of data, not for individuals doing one off things. The corporate enthusiasm for obscuring faces and number-plates in individual bits of footage, like news reports, is really a bit of over zealousness on behalf of bored corporate lawyers. I mean, you walk down the street every day and can read every number-plate on every vehicle and the world doesn't come to an end. Big databases like street view - now that's a completely different matter. This one off photo doesn't bother me, and there's people in government who would, I'm sure, describe me as a pain in the arse privacy activist.
Yes, but the time, place and number plate are visible. If the owner got into a divorce situation because of this information or fired because he was supposedly somewhere else, then they may come after the person who made the information public without permission.
McBryce.
No, no liability attaches. It is quite lawful to take a picture of anybody or anything, anywhere and at any time in Britain if you are taking it from public land or land you have lawful access to and publish it how you will. The one exception is if you see a notice saying "This is a restricted place within the meaning of the Official Secrets Act.
etc. etc.". If it had a caption saying "This cheating bastard is on his way to his lover" you'd be on different grounds, but it doesn't, and anyway that would be defamation.
There are zillions of news photos of major events that clearly show time and place and document the presence of dozens, perhaps hundreds of identifiable individuals. Are you really trying to say that the law or liability avoidance requires every news photographer and picture editor to blur the faces of everybody except the public figures in case one of them is where they shouldn't be?