By Paul Greaves Lady Louise Windsor has been seen at one of the royal’s favourite annual events – riding a muddy electric bike. The rarely-seen granddaughter of the late Queen Elizabeth was snapped today while out and about at the Royal Windsor Horse Show. It was quite a family gathering in the grounds of Windsor Castle with mum Sophie, Duchess of Edinburgh and dad Prince Edward nearby. It comes just a day after King Charles was seen at the show hugging niece Zara Tindall. Lady Louise was spotted on a ENGWE EP-2 Pro bike. She seemed to be helping out at the show and was wearing a Royal Horse S…