"Enhancing the 1907 UK Census of Production for International Plant Size and Labor Productivity Comparisons. "

I propose a rough-and-ready solution to the common lament that prior to 1930 UK censuses of production did not report the sizes of manufacturing plants nor their labor productivities by size classes. Using hitherto neglected Home Office reports on manufacturing plant numbers and employment and matching some with the industries described in the UK’s first (1907) census of production, produces plausible estimates of mean plant sizes for many UK industries, to complement those long available in foreign manufacturing censuses of the early 20th century. UK plants (challenging quantitatively unsupported Chandlerian stereotypes) were typically larger than those in the US or continental Europe, but UK industries with larger mean plant sizes were only mildly positively associated with high labor productivity (sterling net output per head), despite unsupported assertions to the contrary in the 1907 census final report. There were scale economies in municipal coal gasification (a doubling of inputs, over the input range of our sample, increased output by around 114-115%). But firm size and productivity were not obviously associated in private enterprise shipbuilding, an industry in which the UK continued to dominate global production and productivity (for modern propellor-driven iron/steel steamships, though possibly not sailing ships, rowing boats and paddle steamers): regional location near low-cost technically advanced input networks (especially on the Scottish Clyde and northeast England) and warship specialisation (mainly production for the Royal Navy) were more notable productivity drivers than input volumes there.