As gness previously said .. if you have a lawn in Ireland then you would be known as posh.
Imagine you thought you were posh and owned a lawn .. then you would not want the other commoners parking on it, because they wouldn't recognize a lawn if they seen one .... grass is grass tp most people, but not to posh people !
Bet they were anti parking thingys .. something easily created and something you wouldn't drive your car over. Painted white so you can see them when you are driving over the lawn at night on your way back from the pub !