This paper constructs and estimates a vintage model of production for manufacturing in the U.K. including the investment and scrapping decisions. The model uses a generalised Leontief flexible functional form, which allows for the testing of ex-ante and ex-post substitution. The data does not allow the rejection of some substitutability at both ex-ante and ex-post stages. The model also allows for an examination of price responsiveness of input-output coefficients. Finally the model is used to construct a capacity utilisation index.