This third case in the series that begins with “Design Thinking in Action (A): South Western Railway” (UVA-S-0377) describes two waves of experimentation undertaken by UK railway operator South Western Railway (SWR) and its design-consultancy partner, DK&A, during the deliver stage of their joint project to improve customer experience at SWR. They had followed a classic design thinking methodology, discovering customer experiences and needs, defining journey maps and personas, and developing concepts. In this final case, they tested those concepts in actual rail stations to determine whether they met goals for desirability, feasibility, and viability.