This plant is commonly known as ‘Fireweed’ and can be found throughout most of North America. There is also a Dwarf Fireweed. An interesting history can be found in the United States Department of Agriculture Forest Service website(USDA Forest Service) www.fs.fed.us/wildflowers, which states “The name fireweed stems from its ability to colonize areas burned by fire rapidly….fireweed quickly colonized burned ground after the bombing of London in World War II, bringing color to an otherwise grim landscape.”

Welcome to the forum Sam! This beauty looks like rosebay willowherb (Chamerion angustifolium). We are glad to help anyone with gardening questions. Thanks to your post, we get to see what a lovely view of England landscape. Your dog is a lucky pooch! Best wishes! http://wildflowerfinder.org.uk/Flowers/W/Willowherb(Rosebay)/Willowherb(Rosebay).htm