Hundreds more daily train services are being cut in response to pandemic-related staff shortages.
Several other operators have taken the same measure in recent weeks due to the impact of the Omicron coronavirus variant.
It was estimated earlier this month that around 10 per cent of rail staff were absent from work.
South Western Railway’s emergency timetable will see it operate 28 per cent fewer weekday trains compared with pre-pandemic levels.
That is compared with the 17 per cent reduction in its most recent timetable.
The firm’s managing director, Claire Mann, said the change is “the most effective means of ensuring our customers receive a reliable service”.
Avanti West Coast will only run one train per hour in both directions on each of its routes connecting London Euston with Birmingham, Glasgow and Manchester.
Just one daily return service will operate between the capital and Holyhead in North Wales via Chester.
East Midlands Railway said it is removing 4 per cent of services from its timetable as short-notice cancellations are “incredibly frustrating” for passengers.
This will “protect” those trains which are “important for customers who are still travelling”, it added.
Sixteen services will be removed from the weekday timetable of c2c, which operates between London Fenchurch Street and south Essex.
Industry body the Rail Delivery Group said reliability has been boosted by those operators which have already reduced services.
It added that just 2.1 per cent of all trains were cancelled in the seven days to Friday, which is below the annual average of around 3 per cent.
Passengers are advised to check for updates before setting out on their journey, or sign up for automatic alerts from National Rail Alert Me.
Provisional Department for Transport figures show demand for rail travel was at 55 per cent of pre-pandemic levels earlier this week.