Alan Fletcher, who helped revive postwar British design and typography through his vibrant corporate identity work and book designs and who was a co-founder of Pentagram, London’s first major international design consultancy, died on Sept. 21 at his daughter’s home in East Sussex, England. He was 74.

The cause was cancer, his daughter, Raffaella Fletcher, said.

One of the powerhouses of contemporary British business and cultural graphic design, Mr. Fletcher was as well known in England as Milton Glaser is in New York, creating high-profile campaigns for clients like Reuters and the Victoria and Albert Museum. He wed the Modernist European tradition with the emerging pop culture by combining vernacular and artistic elements in his work. The value he added to his posters, book covers, advertisements and even architectural sign systems was that of entertainment and flair.

Although influenced by the Bauhaus, his work never mimicked that style; he made a definite break with the somberness of postwar English Modernism by making compositions that were routinely playful. His colorful stencil signs for the interior of Lloyd’s of London building, which he said were inspired by Le Corbusier, gave Richard Rogers’s mammoth steel-and-glass structure a much-needed warmth.
In the 1996 monograph “Beware Wet Paint” (Phaidon Press) by Jeremy Myerson, Mr. Fletcher exhibits a signature abandon that set him apart from many mainstream designers. His expressive, childlike drawings and paintings are often combined with sophisticated typographical treatments.

For Mr. Fletcher, nothing was as important as the idea.

“Underlying the traits which characterize his work,” Mr. Myerson wrote, “there is one governing theme, the search for the concept.”

In his 1968 logo for Reuters news agency, for instance, each letter is made up of punch-cut dots reminiscent of news tickertape. The logo, in use until 1996, is a testament to Mr. Fletcher’s conceptual timelessness.

Another conceptually startling work, a 1962 poster for his longtime client Pirelli tires, was designed to be posted on the upper level of London’s double-decker buses just under the windows: it shows the below-window-level bodies of sitting passengers.

Mr. Fletcher created visual mind-games that induced double takes in viewers. Yet despite a distinctive design methodology he avoided having a rigid style.
“Style is a curious word because it can mean all sorts of things, from mannerism to charisma,” he told English design critic Rick Poynor. “However, as far as I’m concerned, either what you’ve done has panache or it hasn’t. You can’t design panache.”

Alan Gerard Fletcher was born to a British family in Nairobi, Kenya, in 1931. He was 5 when he moved to West London, where he was raised by his mother and grandparents after his father’s sudden death. Although he attended a boarding school that routinely channeled students into the army, the church or banking, he chose to be an artist.

After graduating from the Central School of Art and Design in London, Mr. Fletcher did more advanced work at the Royal College of Art; upon graduation, in 1956, he was awarded a scholarship to Yale’s graduate design program, where he studied with Paul Rand, Herbert Matter and Josef Albers. In his two years at Yale, he absorbed as much of American graphic design as possible and also met his wife, Paola, who survives him, along with his daughter and a grandson.

He worked briefly for the film-title designer Saul Bass in Los Angeles, and in 1959 he returned to London, where he and Colin Forbes opened a small design studio with clients that included Time and Life magazines and Pirelli. A year later they teamed up with the American designer Bob Gill to found Fletcher/Forbes/Gill. Soon, their sly wit and graphic humor were being written up in magazines like Vogue and clients were clamoring for their services.

In 1965 the studio became Crosby/Fletcher/Forbes when Mr. Gill left and the architect Theo Crosby joined the concern, thereby creating an interdisciplinary practice.

They added two more partners. In 1971, realizing it was impossible to continue adding surnames to the shingle, Mr. Fletcher, after reading a book on witchcraft, coined the name Pentagram, meaning a five-pointed star, one for each partner. The partners adopted it despite some unease about the association with witchcraft.

Soon the quirky partners were creating identities for the Commercial Bank of Kuwait and the signage system for the Victoria & Albert Museum.

Pentagram established offices in New York, Texas and California in the 1980’s, but by 1991 Mr. Fletcher decided to quit. Caught in a cycle of taking on assistants to complete large projects and then needing to take on more large projects to pay these new employees, he sold off his share of the firm and established a small studio in the Notting Hill section of London. He retained a few clients, like the Novartis Campus, the pharmaceuticals complex near Basel, Switzerland. He was also consultant art director for Phaidon Press.

Mr. Fletcher was a co-author of “Identity Kits: A Pictorial Survey of Visual Signs,” “Graphic Design: Visual Comparisons” and “A Sign Systems Manual, ” all published by Studio Vista. As consultant art director for Phaidon, he was responsible for books exploring design history, theory, and process, including Phaidon’s Art & Ideas series. His own book “The Art of Looking Sideways” (Phaidon, 2001) is an exhaustive compendium of inspirational quotes and excerpts from hundreds of artists, designers and thinkers.

“This book has no thesis, is neither a whodunit nor a how-to-do-it, has no beginning, middle or end,” Mr. Fletcher wrote in his introduction. “It’s a journey without a destination.”

At the time of his death, he was putting the finishing touches on his second monograph, “Picturing and Poeting.” He died wearing a T-shirt with handwritten words taken from one of his posters: “I don’t know where I’m going, but I’m on my way.’