In response to the COVID-19 pandemic, a temporary change in policy was implemented in 2020. Breast screening services in England were advised to change from timed appointments to an open invitation for invitees to contact the service and arrange an appointment. This change to invitation methodology had potential benefits and risks including impacting inequalities in uptake. Qualitative data were collected by online questionnaire from 23 service providers and routinely collected quantitative uptake data were analysed to investigate the impact of open invitations on the National Programme in the South of England. Office for National Statistics and general practitioner (GP) practice profile data enabled the modelling of sociodemographic characteristics of breast screening invitees at each GP practice. Most services changed to open invitations (17/23), 82% of which altered administrative capacity and/or procedures to accommodate this change. Logistic benefits were reported including a more consistent flow of participants, fewer long gaps and fewer wasted slots. The change to open invitations was associated with a 7.2% reduction in the percentage of participants screened, accounting for participant sociodemographics and historical screening provider uptake. The inequality in screening uptake experienced by participants of minority ethnic background was exacerbated by the change to open invitations. Open invitations, whilst affording logistic benefits in an unprecedented pandemic era, were associated with reduced overall uptake and exacerbation of existing health inequality experienced by women of minority ethnic background. The broader impact on services highlighted the need for sustainability of measures taken to accommodate such operational changes.