Arthur Ryan, the retail legend who founded Primark sparking the development of so-called throwaway fashion, is stepping down as chief executive after 40 years.

Ryan, who is in his seventies, is making way for Paul Marchant at the helm of what has become Britain's most popular clothes shop after Marks & Spencer.

He will remain chairman for a short while before beginning retirement in full.

Ryan, regarded as a secretive operator who shuns the limelight, said: "I am extremely proud of all that Primark has achieved. As chairman I am looking forward to working with Paul to ensure the ongoing success and future development of the business."

Primark was founded in 1969 in Ireland when it was called Penneys. Under its parent company Associated British Foods it has grown to have arguably the most powerful influence on British dress sense.

Ryan's departure was expected by City analysts and Cazenove said in a note to its clients: "Paul Marchant is well respected in the industry."

Marchant joined as chief operating officer after four years at New Look. ABF chief executive George Weston said: "Since Paul joined Primark earlier this year, he and Arthur have been working together to drive its growth."