Under current Weights and Measures laws, standard loaves should weigh either 400 or 800 grams. But the EU claims this a barrier to European bakers who might want to sell bread of different sizes in our shops. It is claimed that increased competition will be good for shoppers bringing prices down, but the Federation of Bakers claim this will cause confusion and could drive prices up and any move away from standard loaves will require new equipment. There have never been any proposals from the Commission to scrap the British loaf. There is no EC legislation on the size of loaves of bread, this is in fact a national initiative.
Rules do exist to ensure that the unit price of bread is indicated, regardless of weight.
Directives on indication of prices do not prescribe any particular weight of loaf and specifically confirm that Member States can continue to use traditional bread sizes. It is difficult to see how this has been interpreted as a threat to the British loaf. There may be increased competition but that is all part of the aims of the single market.