The Imperialism of Free Trade was a 1953 article by John Gallagher and Ronald Robinson published in the Economic History Review. The article was influential in the debate concerning the Theories of New Imperialism and claimed that the period of New Imperialism could best be characterised as an informal empire based upon free trade.
For criticism see:Platt, D.C.M., The Imperialism of Free Trade: Some Reservations, The Economic History Review, New Series, Vol. 21, No. 2 (Aug., 1968), pp. 296-306