While searching online the other day for a reasonable fare from London to Glasgow, I have found that there are trains running between Ormskirk and Preston on Sunday 15 July between the approximate hours of 11:00 - 20:00. Historically and to the best of my knowledge, there is normally no Sunday service between Ormskirk and Preston. I have already booked the tickets, so it is showing in website journey planners (the WebTis ones such as GWR, and obviously by specifying "Via Ormskirk"). Furthermore, the Real Time Trains website also shows these journeys as STP workings for that day. On further checking, these trains are also shown to run as STP workings on the 22 July, but none on the 1st or 8th at all. Could somebody explain exactly what is happening here?