Over the Easter Bank Holiday Chiltern Railways are planning to operate a Saturday service on three of the four days of the holiday with a Sunday service on Easter Sunday on both the Aylesbury via Amersham line to London Marylebone and the Birmingham to London Marylebone line:
Good Friday 18th April 2014 : Saturday service.
Saturday 19th April 2014 : Saturday service.
Easter Sunday 19th April 2014 : Sunday service.
Bank Holiday Monday 20th April 2014 : Saturday service.
Further information can be found on the Chiltern Railways web site.