There is strong impetus to optimise wheat nitrogen use (NUE) as fertiliser prices rise alongside worldwide energy price increases. Our work aims to understand wheat nitrogen response by determining fertiliser optimum based on financial return to farmers in both the UK and northern India. The changing profile of elite varieties grown on-farm and the expansion of wheat pre-breeding activity provides an opportunity to introduce new variation contributing to NUE ideotypes. This presentation will describe our work to combine novel genetic variation (from pre-breeding) with both predictive lab-based and large-scale field trial opti-plot nitrogen response determination to test hypotheses relating to improving NUE ideotypes. We demonstrate that the opti-plot method is an effective means to test nitrogen response and to quantify differential genotype x fertiliser interactions. This information is useful for informing optimum fertiliser recommendations to farmers in the UK and India and for the accurate and timely identification of promising pre-breeding germplasm with superior NUE characteristics. In parallel to the quantification of native trait variation for nitrogen response we are also manipulating candidate genes (through transgenics) in order to assess the potential to directly manipulate nitrogen response to optimise yield at varying input levels.