In 1934 Peter Roberts joined the company. All sorts of controls came into force with the declaration of war; the paper control was responsible for allocating scarce supplies of paper and other materials and rationing was introduced.

Walter Robert's died on 9 January 1947 and his nephew John Palliser succeeded him as chairman and managing director. By 1950's transparent film bags became one of the company's major products.

Roberts Mart also became one of the first fully automated makers of paper carrier bags and paper cash bags for banks. Because of the shortage of paper Roberts Mart could not produce enough bags to meet the needs of its customers; once again the retail trade was experiencing fundamental change.

While Roberts Mart still served many traditional customers it was winning business from some of the earliest of the new self-service stores, an idea imported from the United States.

John Roberts died suddenly on 6 May 1954, this left the company with three directors Peter and Ion Roberts and Dudley Mart each taking it in turn every year to act as chairman. This proved to be unsatisfactory and over the next decade or so the company lost its sense of direction.

In 1955 the company made an ill-judged investment in a new litho press and the Sheffield and Birmingham offices were closed in the late 1950's. Things only began to improve when Peter Roberts, with the support of the staff, decided enough was enough and became chairman and managing director in April 1961.