Not actually new. I recall this idea being given a trial run during the 80s. It was scrapped in my area when one of the cardboard policemen was stolen.
Just did a google for any trace of that incident but found another more recent. A cardboard policeman was stolen in Manchester in April 2009. Seems this idea keeps being resurrected and failing, suggesting that police never learn from mistakes.
www.manchestereveningnews.co.uk/news/s/1...liceman_stolen_again