'We want to make a sensory garden.’ I’ve lost count of the times I have been asked to advise on such a request. Who would not want a garden that looked beautiful and offered fragrance, flavours and floral variety in terms of touch, taste and smell? These things are all present in a well-tempered garden, but how often do we overlook the joy of sound, apart from birdsong? It is the gentle and the comforting sounds in the garden that please us the most. 'Chatsworth: The gardens and the people who made them' by Alan Titchmarsh (Ebury, £35) is out now