The Southern network is part of Govia Thameslink Railway (GTR), which is 65 percent owned by Go-Ahead alongside France's Keolis. It has faced widespread criticism from passengers, politicians and the media after months of strikes, cancellations and delays on trains into London.

Go-Ahead said on Tuesday that aside from its GTR contract, its rail and bus operations traded strongly in the July to October period.

Strikes during the period, most recently in October with more due in November, dragged on margins at the company's struggling GTR franchise, said Go-Ahead, but its expectations for the network's performance over the seven-year contract remained the same.

(Reporting by Sarah Young, Editing by Paul Sandle)