It was only when I went online to book a ticket that I realised that the overnight West Yorkshire-Manchester Airport services that operate Monday-Saturday do not run on Sunday mornings, even though there are early morning flights from the airport. Does this reflect wider issues about Sunday working, historical concern over keeping lines available for engineering work or some other reason? On the surface it seems a slightly surprising omission when other airport services such as to Stansted and to Gatwick do operate overnight on Sunday mornings.