The origins of the Chiltern line itself date back to 1899 when Marylebone Station first opened to passenger trains. In 1905 the line via South Ruislip and Beaconsfield was opened and suburban services to High Wycombe. Two decades later, the Great Central Railway became part of the London & North Eastern Railway which signalled the dawning of a new era for the company. When the Great Central main line closed in 1966, Marylebone became a suburban terminus for trains to Aylesbury and Banbury. Today Chiltern Railways is part of Arriva, owned by Deutsche Bahn AG.

Chiltern operates service along five routes: Chiltern Main Line, London to Aylesbury Line, Princes Risborough Aylesbury Line, Leamington to Stratford Line and Oxford to Bicester Line. The rail operator's main terminals are at Birmingham Snow Hill and London Marylebone. Chiltern Railways also operates additional services to London Paddington, Oxford and Kidderminster.

While only Standard Class, the company offers a premium economy "Business Zone" cabin on a small number of Birmingham to London peak-time trains. Passengers willing to pay for a £20 upgrade can sit in a larger seat and receive free refreshments.

A catering service is provided on their busiest trains between the West Midlands and London, shown on the company's timetable. WiFi is also available free of charge on all Chiltern Railways mainline trains.

There are four main types of fare available; Advance, Super Off-Peak, Off-Peak and Anytime tickets. There are also several discounted tickets only available under specific conditions such as the 2 Pay 4 Travel pass that entitles four people to travel together during off-peak time for the price of two adult tickets.

One of the UK's most well-established train companies, Chiltern Railways has been operating service throughout England for over a century.