This paper describes the development of an ultra low NOx (i.e. sub 10 ppmvd) combustion system from the successful completion of a high pressure rig programme, to the installation of the system on a gas turbine in commercial operation. It includes a detailed description of early screening tests for DLN concepts and an explanation of how these were developed on both rig and engine test bed. Specific discussions include the concepts and technology for: 1) NOx reduction 2) Optimisation of premix turndown for carbon monoxide control at part load conditions 3) Control of combustion driven pressure oscillation (combustor dynamics) and the failures resulting from the lack of control. In addition to the DLN aerothermal development, an outline description of the combustor mechanical design and the control and systems modification from the conventional combustion system is given.