For some people, this causes a real problem - if they don't get a booster charge during the day, they can't get back in the evening. As a result, there have been a few instances of unpleasantness where people get back to their car in the evening, only to find it's been unplugged and some other car has been plugged in instead.
In order to reduce the unpleasantness, I have had some business-card sized signs created to be placed in the window of an electric car on charge in a public charging point:
The idea is you fill in the blanks and hopefully your car won't get unplugged before you have enough charge to get you home.
I would also suggest going back and moving your car once you have enough charge, thereby allowing another EV owner access to the plug.
I've also had some 'Thank You' postcards produced that can be given to businesses who have provided you with a plug when you've needed it. They say 'Thank You' to the business and on the back suggest that the business could offer this as a service to their customers in general, with links to the EV Network.
If anyone wants any of these cards, I'm selling a pack of ten of each for a whole 50 pence each, including postage. I've worked out that if I sell 384,924,647 of these I should be able to afford my own private island in the Carribean. Granted, it's a bit of a long shot, but I've got to start somewhere.
If you want some, here is the link: Charging Cards