This job posting is for a Front End Developer at a leading advertising agency in London that has grown rapidly to 700 employees. The role involves building large web applications using the best technologies and collaborating closely with a cross-functional team. Requirements include strong HTML5 and CSS3 skills, experience designing beautiful user interfaces, and understanding of JavaScript, frameworks like Backbone and RequireJS, and agile development practices. The ideal candidate is enthusiastic, a self-starter, and comfortable sharing opinions.