Your questions about company information for Southern answered here...
Southern services are operated by Govia Thameslink Railway (GTR), which also operates the Great Northern, Thameslink, and Gatwick Express services.
GTR is owned by Govia, which is a joint venture between the Go-Ahead Group and Keolis.
The Go-Ahead Group has operated the Govia Thameslink Railway franchise through Govia (a joint venture between Go-Ahead and Keolis SA) since 14 September 2014.
We operate two routes; Great Northern (which connects King's Lynn, Cambridge and Peterborough) and Thameslink, which runs between Bedford, Luton, Sevenoaks, Gatwick and Brighton. Then, in 2015, GTR were joined by Southern and Gatwick Express.