London North Eastern Railway (LNER), who operates the Anglo-Scottish journeys on the East Coast Main Line, will not allow passengers to travel unless they have a reservation.
The government are urging transport operators to rearrange and limit seating “to try and ensure social distancing is observed.”
The train operator are introducing the measures next week to enforce social distancing.
A spokesman said: “The safety of our staff and customers is always our top priority.
“To support social distancing for customers who do need to travel with us at this time, all LNER services will be reservation-only from Monday.”
Avanti West Coast have warned their customers anyone who without a reservation may not be allowed to travel on their choice of train.
Managing director Phil Whittingham said, “We’re appealing to our valued customers to help us and other passengers by only travelling with a reservation.
“If everyone does this, we’ll be able to keep social distancing in place on board, both for our customers and our people.
“If customers do turn up without a reservation, we’ll do our best to help but we can’t guarantee they’ll be able to take the train they want.”
Staff will be wearing face masks and there will be an enhanced cleaning regime for waiting rooms and lounges.
Industry body the Rail Delivery Group (RDG) are urging passengers to avoid non-essential travel after recording a rise in journey planning this week.
Between Sunday and Thursday 3.7m journeys were planned, compared to 3m of the same period the week before.
RDG director of nations and regions Robert Nisbet said, “We need people’s help to keep trains clear for those who really need them, so we are asking people to consider alternatives like cycling or walking, and if that’s not possible, to travel at quieter times.”