Evidence of prior mass production of the Rolls Royce Merlin the preponderance of unskilled labour at Glasgow rendered the factory particularly reliant on up to date production methods and mechanisation Machine tools were arranged and set for single purpose operations and the factory was planned on a flow production basis with the minimum of rehandling Ritchie Sebastian Industry and Air Power The Expansion of British Aircraft Production 1935 1941 Frank Cass 1997 p135 Rolls Royce Glasgow was operational by February 1941 ibid p135 p144