It should have a time limit on it, and the legislation needs to be tightened up to be more specific in the matter of supplementary indicators. People therefore ignore the metric price.
Local authorities are unwilling to challenge the companies in court due to the expense involved.
So the law is being flouted because Trading Standards don t feel they have enough support from the government, in the form of legislation. I have made several complaints to my local TSD about store signs displaying milk prices, which refer only to the size in pints. In addition, it is common for shelf-edge labels to show unit price per pint, again with no metric price. Unfortunately, competitive pressures make stores scared of doing something different to the others. All these problems would disappear if the prescribed quantities list were amended to permit only rational metric sizes.