Monty Don and Joe Swift look at more of the floral exhibits at this year's RHS Chelsea Flower Show. Joining them is presenter James Wong who visits a show garden that pays homage to the Wardian case, the Victorian invention that revolutionised the way plants were transported by the 19th century plant hunters. Plus garden designer Dan Pearson and Thomas Heatherwick, designer of the 2012 Olympic cauldron join Monty to share their thoughts on this year's event