Ray tracing has been used for the investigation of the off great circle propagation of radio signals in a 4490 km West-East path in presence of the mid-latitude trough. Two propagation mechanisms were studied, non-specular scatter from the sea and reflection from the walls of the trough. The results assuming sea scatter are generally in good agreement with observations at a number of frequencies, while ray tracing simulations of reflection from the equatorward wall of the trough do not reproduce the large bearing deviations observed. For additional information about the trough in northern Europe, an experiment between Uppsala, Sweden and Leister U.K. has been established, in which measurement of the elevation angle and time-of-flight characteristics are included to improve and develop ionospheric trough models for this region.