3.23 Delays to services on the central section also have knock-on impacts for the introduction of Elizabeth line services between the Great Eastern and Great Western main lines. Services operating on the surface railway must make applications as part of the national timetabling process, and the delay to Crossrail introduced risks to those services planned to be introduced from May and December 2019. MTR-Crossrail, the Elizabeth line operator, has submitted a timetable bid to operate services between Paddington and Reading from December 2019 to secure its planned service patterns, and there are already services on the Great Eastern Main Line. The date at which through Elizabeth line services will operate has not yet been confirmed.