The Parkin firm modelled itself after the office of Albert Kahn, and used an industrial production system to produce its commissions.

In August 1968, John B. Parkin Associates opened merger discussions with Smith Carter Searle of Winnipeg, which had offices also in Toronto, Brandon, and Thunder Bay.

[6] The firm, known since 1985 as NORR, remains in existence today, with offices in Toronto, Ottawa, Calgary, and Edmonton.

It received several important commissions in the 1970s and 1980s, including the Art Gallery of Ontario addition, the Phoenix Building, Bell Trinity Square, and Copps Coliseum.

In 1986, Harland C. Lindsay and two partners acquired the assets of the firm, and on 17 December that year incorporated Parkin Architects Limited.