An in-vivo x-ray fluorescence (XRF) bone lead analyser, based on the Somervaille design, has been constructed and tested as the first step towards developing a deep bone lead analyser to expand the range of bone tissue available for assessment, to include more deep seated bones such as the femur & vertebrae. These bones represent a major component of the total body bone tissue and therefore the lead body burden. A new test analyser, constructed by modification to the basic design of a superficial bone analyser, has been used to investigate the feasibility of using changes in source-detector geometry and collimation to improve deep bone lead sensitivity for in-vivo measurement techniques. Initial results indicate that the relative detection sensitivity of the test analyser is approximately 6 times that of the Somervaille based system. The results of examination of a series of lead loaded plaster of paris phantoms (0 ppm - 360 ppm) confirmed there was good correlation (r = 0.996, p < 0.0005) between the measured ratio (lead X-rays/coherent scatter photons) and the lead concentrations using data from both XRF analyser systems.