This paper contains the details of an experimental investigation into double lap single bolt tension joints made from 6.35 mm thick pultruded fibre reinforced plastic flat sheet. The joint geometry [edge distance to bolt diameter (E/D) and width to diameter (W/D) ratio] was varied and the effect of bolt clamping torque was investigated. Failure loads, critical end distances and critical widths were found to increase as the bolt clamping torque increased. After an initial bolt movement, the load vs bolt displacement plots are linear until the joints fail or the stiffness reduces significantly. The load at which the joint stiffness reduces has been called the damage load. This damage load is thought to be a useful quantity on which to base design. A simple statistical analysis has been carried out on the damage loads and damage load capacities for single bolt joints have been determined for prescribed confidence levels.