Alan Titchmarsh and Joe swift launch a week of celebrations as the RHS Chelsea Flower Show reaches its 100-year anniversary. On the day when the royal family visit the show, there's a look at a very special show garden commissioned by HRH Prince Harry. We meet the orchid growers who have exhibited at Chelsea every year since 1913 and catch up with the South African exhibitors mirroring the style of one of the show's earliest stands.