Signaller Ms Gammie returned from maternity leave and sought to reduce her hours of work, through flexible working or job sharing. However, Network Rail at this time faced a "manpower crisis": signal-boxes were, at times, being left un-manned (delaying train movements and incurring costs and fines). At this time no signallers in Scotland worked part-time. Network Rail refused her applications, due to (1) additional costs (2) effect on customer service (3) inability to reorganise due to the unique nature of the work and (4) failure to recruit for the job-share attempt.