In Brogden v Metropolitan Railway Company, although the Metropolitan Railway Company had never returned a letter from Mr Brogden formalising a long term supply arrangement for Mr Brogden's coal, they had conducted themselves for two years as if it were in effect, and Mr Brogden was bound.
在Brogden v Metropolitan Railway Company案中， 尽管大都会铁路公司从未给Brogden先生关于长期煤炭供应合作的正式表述回信，他们却确实已经实际实施了两年，已经当作它生效了，因此Brogden先生是受其约束的。