The manoeuvreist doctrine requires that commanders have the freedom to move around the battlespace to locations where they can best influence the outcome. To achieve this, commanders must be secure in the knowledge that they can do so undetected. Infrared (IR) sensors, with ever increasing sensitivity, are now well established in the land environment, IR signature management is therefore becoming evermore necessary for battlefield equipment. High-fidelity thermal signature models are available but require high levels of operator expertise, detailed input data, and they are time consuming to run. A simple, easy to use thermal signature model would provide a ready alternative to the more exacting complex models. Whilst not attempting to replace the high-fidelity models for the detailed analysis of thermal signatures, a simple model would have utility as a first filter of trials data and the initial testing of signature reduction concepts. A single temperature difference model of a Main Battle Tank (MBT), incorporating the emissive and reflective components of its thermal signature, is presented. This model is used as the input into a Minimum Resolvable Temperature Difference (MRTD) model for a generic thermal imaging tank sight which is used to predict the detection ranges of the MBT. The reduction in detection range afforded by emissivity variations is calculated and demonstrates the potential benefits and difficulties of this signature management procedure.