Train journey times between northern English cities could be slashed under proposals put forward by the boss of the £50 billion HS2 high-speed rail project.
The improvements would cover an east-west section of northern England and would be in addition to the north-of-Birmingham phase two of HS2 which will see a Y-shaped route going to Manchester and Leeds.
HS2 Ltd chairman Sir David Higgins said northern connectivity plans - dubbed "HS3" and backed by Prime Minister David Cameron and Chancellor George Osborne - would be "as important to the north of England as Crossrail is for London".
The plans, if carried forward, would mean journey times between Leeds and Manchester could almost be cut in half while journeys between Leeds and Birmingham, Leeds and Sheffield Meadowhall, York and Birmingham and Nottingham to Birmingham could also be reduced by a half or more, and many more journeys across the country substantially shortened.
Phase one of HS2 involves a new high-speed line from Euston in London passing through Tory heartlands in the Chilterns to Birmingham, with an expected completion date of 2026.
Phase two was originally scheduled to be completed in 2032/33, although Sir David is keen for this date to be brought forward.
The project is strongly supported by the Government but is bitterly opposed by some councils and residents along the phase one route.
Sir David's four main proposals are:
:: Need to take forward both legs of the proposed HS2 Y-network - the alternatives will not bring the same capacity, connectivity and economic benefits;
:: Improve the rail services between east and west - sharply reducing journey times between Liverpool, Manchester, Leeds, Sheffield and Hull will stimulate local economies. Sir David says the journey from Leeds to Manchester could be cut from today's average of more than 55 minutes to somewhere between 26 and 35 minutes, depending on which option is chosen, and the number of trains could be doubled;
:: Northern cities should speak with one voice - local authorities from five key cities should join together to form a new body. Sir David suggests calling the group Transport for the North.
:: Set out a timetable to develop a new transport strategy to decide on an approach for improving rail and road connectivity across and within the region north of Birmingham.
In addition to these recommendations, the report sets out a series of conclusions from Sir David's review of the proposals for phase two of HS2. These include:
:: To continue with the planned route into Manchester city centre via the airport - keeping open the option to add a new airport station;
:: Need to review the best station solution for Leeds to include provision for increased east-west services through the city;
:: The HS2 line should be extended to Crewe by 2027 - six years earlier than originally proposed;
:: A new station at Sheffield Meadowhall remains the best way to serve the wider South Yorkshire region, though Sir David recognises Sheffield continues to argue for Sheffield Victoria;
:: That the East Midlands hub should be near the proposed site at Toton but that its precise location needs further work.
Sir David said: "Improving connectivity is vital if Britain is to compete in the knowledge economy in which this country has a competitive advantage, but in which ease of travel is an essential element.
"Knowledge-based companies whether they are in high-tech manufacturing, the creative industries, finance or the law, have to be close, or feel close, to the talent, skills base, support network, knowledge pools, collaborators and clients necessary to create the "hot-house atmosphere" in which they thrive.
"That is why reducing the journey times between and within our cities isn't just desirable for both passengers and freight. It is a strategic necessity."
Mr Cameron said: "Improving connectivity and reducing journey times between our great northern cities is a crucial part of our long-term economic plan for the north to boost businesses and create more jobs and security for hard-working people. That's why we are backing HS3.
"I welcome Sir David Higgins' report which will help our work to create a northern powerhouse and ensure that HS2 delivers the maximum economic benefits."
Mr Osborne said: "The vision I set out earlier this year of the northern powerhouse we could build is rapidly taking shape.
"I asked Sir David to look at how we deliver the better transport links across the north that would make a reality of that powerhouse.
"I'm delighted with the rapid response and the report. Today we take another big step forward in delivering both the HS2 links from north to south and the HS3 link across the Pennines.
"On the back of new transport infrastructure, science investment and civic leadership, we are well on our way to turning the northern powerhouse into reality."
Transport Secretary Patrick McLoughlin and Chief Secretary to the Treasury Danny Alexander also welcomed the report, as did House of Commons Transport Committee chairman Louise Ellman.
She said: "HS2 is important strategic infrastructure but must be linked with improvements in the classic rail network to bring maximum benefit.
"Sir David Higgins is also clear that HS2 should be part of a wider national transport strategy, as the Transport Committee has recommended.
"These proposals are a welcome boost to northern economies and should be followed by investment following discussions with local authorities and businesses."
A spokesman for the Rail Delivery Group, representing Network Rail and rail operators, said: "Our railway has been transformed in the last 15 years and phenomenal growth in passengers and goods moved by rail is playing a crucial role in keeping the nation competitive in a global economy.
"Sir David Higgins' report underlines how HS2 will become the backbone of Britain's growing railway, linking up our major northern cities and helping to meet the challenge of demand for more passenger and freight services."
Stop HS2 campaign manager Joe Rukin said HS3 would be even more expensive per mile than HS2.
He added that Sir David's report "showed that the original plans for HS2 weren't thought through properly".
Mr Rukin went on: "Changing the mess that is phase two doesn't change the fact that phase one is still a complete mess, as is the entire concept of HS2."
Deputy Prime Minister Nick Clegg welcomed the announcement and said the proposals must now be implemented.
He said: "I strongly welcome the fact that this report lays to rest, once and for all, the claims made by those who don't believe that high speed rail should pass through South Yorkshire by way of the eastbound link.
"Detailed analysis shows that this is vital for the Yorkshire economy and it must now be delivered.
"I also welcome David Higgins' call for all communities and local authorities in the north of England to work together to develop plans for better east-west links.
"There's no point developing north-south links without promoting the connectivity of the cities in the north."
Shadow transport secretary Mary Creagh said: "Labour supports high-speed rail to tackle commuter overcrowding and to improve connections between cities in the north and Midlands and London.
"We have repeatedly said we need value for money for the taxpayer and to improve the existing plans to maximise the benefits for the whole country."
She went on: "Hard-pressed travellers in the North will judge David Cameron on his actions, not words.
"Under his Tory-led government rail fares have risen recently by up to 162% for northern rail passengers and there are plans to cut vital east-west services from Cleethorpes, Grimsby and Scunthorpe to Manchester.
"Only a Labour government will cap rail fares, legislate for a public-sector operator, devolve the running of regional and local services and deliver a railway which puts passengers first."
Cllr Keith Wakefield, leader of Leeds City Council, described HS2 as "the key to transforming the future economy of Leeds and the north".
He said: "It offers huge benefits in terms of job creation and opportunities, driving growth and innovation and bringing people and places closer together, making cities like Leeds and the wider city regions much more attractive for businesses to base themselves.
"However, just as important in Sir David's report is the endorsement of the One North proposals and the need for a fully integrated national transport strategy."