This study investigates spatial accessibility inequalities within Greater London, with a focus on zone-specific disparities between individuals with mobility impairments and the general population. The research examines how architectural barriers, particularly steps and gaps, impact the use of public transportation networks. To quantify these inequalities, Hansen's and Shen's indices are employed as measures of spatial accessibility. A consequent comparative analysis is made assuming that disabled individuals can only utilise step-free services, through lifts and same-level paths, while the general population has access to all services and interchanges. The findings shed light on the unequal accessibility experienced by mobility-impaired and elderly individuals compared to the general population.