Fired Earth has launched the National Trust range of paints, inspired by the houses and gardens in its care. The collection is available in ‘hardwearing emulsion’ and acrylic eggshell (in some colours); I am guessing from your email that you would like an oil-based or masonry finish. Also consider the English Heritage collection from The Little Greene Paint Company and the excellent deep rich colours from Mylands. You might contact Designerpaint, a family business that sells most major brands of paint, including Zoffany and Sanderson. They offer excellent advice and have over 130 stores nationwide.