United Kingdom restaurants to include calorie information on menus

Here in United Kingdom, the Government is encouraging restaurants agreement include calorie counts on their menus.
But effective it is likely to be?
The scheme is currently voluntary, but if companies did not cooperate, the Government can adopt legislation to implement the conformity.
The changes are likely to come into effect in September:

Restaurants, impressions, cafes, bars and sandwich shops signed up to put calorie labelling in their menus to eat and to prepare them since September this year.

It seems a good movement, empowering consumers make wise decisions. The Government feels will address the problem currently facing many dieters: meals prepared at home are easy to count calories as packages are labelled, but meals consumed in cafes staff, canteens and restaurants must be "guesstimated" at best.
The problem is, a small study of America suggests a similar scheme necessarily did not work. The researchers have published their results in the International Journal of obesity.
427 of low-income parents and adolescents were surveyed about their fast food habits before and after the introduction of calorie labelling. While many parents and adolescents noted information, some of them (9% of adolescents and 28% of adults) were considered at the checkout. In general, the number of calories consumed were the same as the introduction of calorie labels.
Even when calorie information is present, it is far from the only thing consumers will take into account. "Flavour" and then on "price", were the main factors considered by parents and adolescents in this study.
Local restaurants have calorie information? If so, it makes a difference to what you ask?
Image credit: Yaletown Business Development Association