McDonald’s is celebrating 50 years in the UK with a month-long range of surprises such as the launch of an exclusive ‘I Had My Birthday Party at McDonald’s’ range, a first ever merch pop-up, a retro birthday party ad, special items added to the menu, surprises in stores, digital party bags, tastings of the Grimace Shake and more. “McDonald’s 50th birthday” multimedia campaign is created by Leo Burnett UK and includes a 60-second film ad…