Postbag Edition: Mary Berry's House

Peter Gibbs and the GQT panel have traded parks and community gardens for a visit to the Oxfordshire home of Dame Mary Berry. On this week's panel are Matthew Pottage, Christine Walkden and Bunny Guinness. Among today’s questions, the panellists troubleshoot evergreen roses plagued by black spot, unravel the mystery of why clematis keep failing on one side of a small London garden, and help a…