The union is appealing that ruling, but legal experts suggest it is unlikely to prevail. Royal Mail said it has been in touch with the Communication Workers Union and is open to talks. It said: “Industrial action, or the threat of it, can only hurt our company, and our colleagues.” The shares, which floated at 330p in 2013 and roared to 489p on the first day of trading, fell 40p to a new low of 191p.