Lead tungstate phosphate glasses are of practical interest due to their electrochromic and photochromic properties, with a wide range of practical applications in smart windows, display devices and sensors. This is a relatively complex ternary glass forming system, and there is only a limited amount of information known about the structure of these glasses. Attention has focused on the role of tungsten, and in particular the possibility of W-O-W bridges (associated with clustering of tungsten) and terminal W=O bonds. Despite the complex composition of these glasses, they are amenable to study by neutron diffraction; the proposal shows that it will be possible to observe terminal W=O bonds, and to determine the tungsten environment by neutron diffraction.