I'm getting a bit confused. I'm planning a daysave trip this week to explore some of the network I've not been on. On Saturday, I can find northbound trains to MKC quite easily, they are from East Croydon at 7 minutes past the hour and are marked as SN / Southern services. (e.g this service on RTT) However on the return journey, they are at 13 minutes past the hour but are marked as TL / Thameslink trains (the return service of the above is here on RTT). Given that a daysave is only valid on Southern services, does this mean I can use it to get to Milton Keynes but not back? I'm sure that can't be right but I don't want to risk a penalty fare!