This paper describes the development of liquid crystal light valves (LCLVs) using bismuth silicon oxide (BSO) as the photoconductor at the Sowerby Research Centre of British Aerospace. The results of two LCLVs are presented and compared, both of which use a 250 micrometre thick slice of BSO. The variation in time response with liquid crystal viscosity is investigated. A resolution of 27 line pairs/mm (50% MTF point) was obtained for the first device. However, refinements in fabrication and measurement techniques yield a resolution of 31 line pairs/mm for the second light valve.