Extra trains are promised on the railway line between Brighton and London by Southern.
The train operator said that it would run extra hourly trains on Sundays when the summer timetable starts on Sunday 22 May.
The extra trains will run until Sunday 4 September, leaving Brighton for London Victoria at 9.10am and then hourly until 8.10pm.
There will also be an extra hourly service from Victoria to Brighton leaving at 9.36am until 8.36pm.
Some trains between London and Brighton will be retimed on Mondays to Saturdays.
For example, the service leaving Victoria at 9.21am and hourly until 3.21pm will be retimed and will also stop at Burgess Hill. The new departure time from Victoria will be 8.51am and hourly until 3.51pm.
And the 9.58am service from Brighton to Victoria, which runs until 3.58pm, will also be retimed and will also stop at Burgess Hill. The new departure time from Brighton will be 9.25am and hourly until 3.25pm.
On Sundays until Sunday 4 September trains between Brighton and Portsmouth Harbour will also be retimed to run earlier.
Southern said that in May customers can take advantage of a 26 per cent discount on advance and off-peak fares when bought online at southernrailway.com.
For all the changes, see the new timetable which can be downloaded at www.southernrailway.com, with hard copies available at Brighton, Hove and Portslade stations. It will remain valid until Saturday 10 December.
Earlier the Association of Train Operating Companies said that the number of passenger journeys had risen 5 per cent in the first three months of this year.
The increase comes at a time of high petrol prices and the figures compare with a period, 12 months earlier, when snow affected passenger numbers.
