A large RCT (FIM12) and several real world studies have shown trivalent influenza vaccine high dose (TIV HD) to be more effective than standard dose trivalent influenza vaccine (SD) in terms of reducing influenza cases and hospitalisations, including serious cardio-respiratory events (CREs), in the elderly population. The aim of this study was to estimate the public health and economic impact of switching from SD to TIV HD for adults aged ≥65 years in England and Wales using econometric modelling. An age-structured decision tree model comparing multiple vaccination strategies was designed in Microsoft Excel. Model outcomes included influenza cases, influenza-related GP consultations, hospitalisations, and deaths. Two alternative hospitalisation definitions were used; respiratory hospitalisations attributable to influenza, and CREs (possibly attributable to influenza). All analyses were conducted from the UK healthcare system perspective. The model was populated with FIM12 clinical trial data and demographic, epidemiological, and economic inputs appropriate to the UK setting. Deterministic sensitivity analysis (DSA) was performed to assess the robustness of results. In England and Wales, switching from SD to TIV HD (in adults aged ≥65 years) was associated with a reduction of 75,000 cases of confirmed influenza, 19,000 influenza-related hospitalisations, and 4,000 deaths, in an average influenza season. Using thresholds of £20,000 and £30,000/QALY, TIV HD was estimated to be cost-effective at £23.75 and £30.70 per dose, respectively. The cost-effective price at £20,000/QALY increased to £115.15 when accounting for the vaccination effect in reducing CREs. DSA showed that these results were most sensitive to relative vaccine efficacy against influenza hospitalisations whereas the remaining parameters had a low impact on model outcomes. The results suggest that the inclusion of TIV HD on the influenza vaccination schedule has the potential to be a highly cost-effective intervention for the UK healthcare system and would contribute positively to improving public health goals.