He founded a design firm called 'Fletcher/Forbes/Gill' with Colin Forbes and Bob Gill in 1962. An early product was their 1963 book Graphic Design: A Visual Comparison in John Lewis's Studio Paperbacks series. Clients included Pirelli, Cunard, Penguin Books and Olivetti. Gill left the partnership in 1965 and was replaced by Theo Crosby, so the firm became Crosby/Fletcher/Forbes. Two new partners joined, and the partnership evolved into Pentagram in 1972, with Forbes, Crosby, Kenneth Grange and Mervyn Kurlansky, with clients including Lloyd's of London and Daimler Benz. Much of his work is still in use: a logo for Reuters made up of 84 dots, which he created in 1965, was retired in 1992, but his 1989 "V&A" logo for Victoria and Albert Museum, and his "IoD" logo for the Institute of Directors remain in use. In last years he designed the logo for the Italian School of Architecture "Facolta' di Architettura di Alghero",. In 1962, he co-founded British Design & Art Direction, along with David Bailey, Terence Donovan, which was later renamed Designers and Art Directors Association. He left Pentagram in 1992, and worked from the home in Notting Hill that he had occupied since the early 1960s, where he was assisted by his daughter Raffaella Fletcher, Leah Klein and Sarah Copplestone, and worked for new clients, such as Novartis. Much of his later work was as art director for the publisher Phaidon Press, which he joined in 1993. For him, life and work were inseparable: "Design is not a thing you do. It's a way of life.". He would continue working, even on holiday, drawing on a notepad with a pencil. A book of his designs, Beware Wet Paint, was published by Jeremy Myerson in 1994. Fletcher also wrote several books about graphic design and visual thinking, most notably The Art of Looking Sideways, which had taken him 18 years to finish. An exhibition of his life's work was displayed at the Design Museum in London between 11 November 2006 until 18 February 2007, alongside the posthumous publication of a book, Picturing and Poeting. The exhibition went on tour in 2008. It was installed at the Ginza Graphic Gallery in Tokyo between 9 and 31 May 2008, and was installed at the Pitzhanger Manor Gallery in Ealing, West London, between 14 November 2008 and 3 January 2009. He won the 1993 Prince Philip Designers Prize given by the Design Council, was President of the D&AD in 1973 and International President of the Alliance Graphique Internationale from 1982 to 1985. He was elected to the Hall of Fame of the New York Art Directors Club in 1994, was a senior fellow of the Royal College of Art in 1989 and became an honorary fellow of the London Institute in 2000. The December 2006 limited-edition cover of Wallpaper* magazine featured one of his last works omitting his calligraphic signature in the compliments slip accompanying his completed work for he was too frail by then. He died of cancer in London, and is survived by his wife and daughter.