On the eve of the opening of this year's event, Diarmuid Gavin is in Cheshire for a sneak preview of this year's show gardens and back-to-back plots. Monty Don and Charlie Dimmock catch up on some of the exhibitors in advance of the start, plus a look at the competition's history. Coverage of the event itself is on Thursday at 7.30pm.
Producer Karen Mackinder www.bbc.co.uk/gardening RT Shop - giant clematis collection: page 44