Today the British Board of Film Classification confirmed the runtime and rating for SPECTRE on their website.
The BBFC notes that the film makers were given advice during post-production in order to secure a 12A rating. An early cut was likely to have received a 15 rating and so some changes were made to secure the 12A classification. The changes concerned one scene of violence and another showing the aftermath of a violent act.
Running time is confirmed as 148 minutes (2 hour 28 minutes), longer than the 141 minute running time of Casino Royale, previously the longest Bond movie.