Yes I get that, but why now...why are the children this year more precious than previous years?
Is reclassification only done now and again?
BBFC carries out reviews of their classification guidelines in consultation with the public as to public expectations. They've been doing that for some time but I don't think they did back in the days when they were the British Board of Film Censors rather than of Film Censors back in 1984. Presumably those consultations have had concerns raised by parents. The BBFC would say that any reclassification has been as a result of those concerns (outside changes in the law which wouldn't be of any relevance re "The Red Shoes")
BBFC would generally be looking at existing film classifications either when a film is to be re-released in cinemas, released or re-released on DVD/Blu-ray or can be done by the likes of Netflix if they are intending to make a film or programme available. In exceptional circumstances they can make a sudden reclassification decision say if there's been a change in the law. In the case of "The Red Shoes" it's because it's to be re-released in cinemas later this year.