A campaign group is calling for a rolling programme of high-speed rail to support resilience and growth in the national economy.
High Speed Rail Group (HSRG) says the Government should implement a transformative programme across Britain beyond HS2.
Responding to the National Infrastructure Commission's new assessment which will inform the Government's plans, the group said there must be a comprehensive, long-term view to strategic investment in Britain's railways.
Following the delivery of HS2 phases one and 2a expected in the 2020s, it says there must not be a delay in the construction of Phase 2b, or to the delivery of complementary programmes including Northern Powerhouse Rail and Midlands Engine Rail.
Phase one of HS2 will run between London and Birmingham, phase 2a will go between Birmingham and Crewe and phase 2b from Crewe to Manchester and Birmingham to the East Midlands and Yorkshire.
If necessary, these projects should be split into smaller subsections and phases to accelerate delivery, HSRG says.
It added that connectivity with Scotland should also be viewed as essential.
"Pursuing high speed rail for Anglo-Scottish travel not only makes economic sense but will help achieve ambitious carbon reduction targets," it said.
"A programme of line of route upgrades delivered in combination with new sections of high-speed line to bypass slow and congested sections of route is needed.
"In addition to environmental gains, this will play a role in levelling up the economy and providing capacity where it is evident that market demand will continue on an upward trend over the coming years."
HSRG, which represents companies with experience of and an interest in high-speed rail, is also calling for a high capacity fully electrified railway.
Its statement added: "As a group, we believe that the commission's assessment should be as broad as possible in order to take the fullest view of the transformative opportunities from investing in a new Midlands and Northern rail network, as well as Anglo- Scottish travel, and build a comprehensive, long term plan which can be delivered in digestible steps.
"New rail networks bring with them transformative capacity, connectivity and carbon benefits. As we look ahead to a post-COVID 19 world, we must therefore consider a rolling high speed rail programme as essential to the future of the country."
