This report provides a comparative analysis of Marks & Spencer (M&S) and Sainsbury's, two major British retailers. It begins with an overview of both organizations, followed by a financial analysis using key performance indicators (KPIs) such as sales performance, profitability (gross and net margins), free cash flow, debt and investment, market share, and price-to-earnings ratio. The report then delves into strategic issues using PESTEL analysis, a modified Porter’s 6 forces model, and the Balance Scorecard (BSC) for both M&S and Sainsbury. An appraisal of the limitations of financial and conventional modeling is included. Based on the analysis, recommendations are provided to M&S to improve its overall performance. The report concludes with a summary of findings and a list of references.