[8][9] The High Speed Rail (London - West Midlands) Act 2017, authorising the construction of Phase 1, passed both Houses of Parliament and received Royal Assent in February 2017.

[15] The DfT has forecast that improved connectivity will have a positive economic impact, and that favourable journey times and ample capacity will generate a modal shift from air and road to rail.

[19][20] Oakervee's conclusions were that the original rationale for High Speed 2—to provide capacity and reliability on the rail network—was still valid, and that no "shovel-ready" interventions existed that could be deployed within the timeframe of the project.

The House of Commons Public Accounts Committee, in a January 2024 report, in relation to the revised planned route, stated that:"HS2 now offers very poor value for money to the taxpayer, and the Department [for Transport] and HS2 Ltd do not yet know what it expects the final benefits of the programme to be".

After progressing through a tunnel bored under Long Itchington Wood, the route will pass through rural areas between Kenilworth and Coventry, crossing the A46 to enter the West Midlands.

North of the station west of Coleshill there will be a complex triangular branch junction, with six tracks at one section, will link the HS2 Birmingham city centre spur with the main spine.

This connection allows HS2 services to serve the cities of Liverpool, Manchester and Glasgow on a mix of new high-speed track and the existing West Coast Main Line.

[49][50][51] High Speed 2 is to share a southern terminus with the West Coast Main Line at London Euston, which is to be remodelled to integrate six new HS2 platforms and concourse with the current conventional rail station.

The report concluded that, although initial outlay on commissioning new rolling stock would be high, it would cost less than the widespread disruption of rebuilding large tracts of Britain's rail infrastructure.

[161] In 2014, the most commonly cited cost applied to the project was £56.6 billion, which corresponds to the June 2013 funding package, as adjusted for inflation by the House of Lords' Economic Affairs Committee in 2015.

[182][181] A 2008 paper, "Delivering a Sustainable Transport System", identified fourteen strategic national transport corridors in England, and described the London – West Midlands – North West England route as the "single most important and heavily used" and also as the one which presented "both the greatest challenges in terms of future capacity and the greatest opportunities to promote a shift of passenger and freight traffic from road to rail".

[194][195] In a report brought out in 2019, the High Speed Rail Industry Leaders group (HSRIL) stated that in order to meet 2050 carbon emissions targets, HS2 must be built.

[205] In 2017, a protest camp was established at Harvil Road in the Colne Valley Regional Park by environmental activists intending to protect the wildlife habitats of bats and owls.

[207] In early 2020, during the clearance of woodland along the route, the group HS2 Rebellion squatted on a site in the Colne Valley, aiming to block construction; the protesters argued that public money would be more suited to supporting the National Health Service during the COVID-19 pandemic.

[213] In the spring of 2021, the Bluebell Woods Protection Camp was set up at Cash's Pit, adjacent to the A51 road, on the line of the proposed route as it passes north of the village of Swynnerton in the county of Staffordshire.

Amid concerns that HS2 was carrying out preparatory works during nesting season, Springwatch presenter and conservationist Chris Packham filed for a judicial review of the decision to proceed and an emergency injunction to prevent construction, having crowdfunded £100,000 to cover legal fees.

The paper questioned the value for money of high-speed rail as a method of reducing carbon emissions, but noted that with a switch to carbon-free or carbon-neutral electricity production the case becomes much more favourable.

[244] The House of Commons Transport Select Committee report in November 2011 (paragraph 77) concluded that the government's assertion that HS2 would have substantial carbon reduction benefits did not stand up to scrutiny.

[9] Others argue these reports do not properly account for the carbon reduction benefits coming from the modal shift to rail for shorter-distance journeys, due to the capacity realised by HS2 on existing mainlines resulting in better local services.

[258] Early discoveries during construction were two Victorian-era glass jar time capsules found during the demolition of the derelict National Temperance Hospital in Camden, dating from 1879 and 1884.

[263] Many of the skeletons were identifiable by surviving lead coffin plates, including the long-lost remains of explorer Captain Matthew Flinders,[264] who is to be re-buried in his home town of Donington, Lincolnshire.

One of the most significant finds was that of a large circular monument of wooden posts 65 metres (213 ft) in diameter with features aligned with the winter solstice, similar to that of Stonehenge in Wiltshire.

[270] In September 2021, archaeologists from LP-Archaeology, led by Rachel Wood, have announced the discovery of the remains of old St Mary's Church in Stoke Mandeville, Buckinghamshire, while working on the route of the HS2 railway.

[273][274][271] In early 2021, a significant site called "Blackgrounds" (for its rich dark soil) was discovered on what was previously pastureland near the village of Chipping Warden in South Northamptonshire, close to River Cherwell.

[275] A team of 80 with the MOLA Headland Infrastructure archaeological consortium, which is working with HS2 Ltd, excavated the site, which consisted of a small Iron Age village that became a Roman town.

[258][275] HS2 Phase One represents the largest single programme of historic environment work undertaken in the UK[276] and has generated a vast amount of digital archaeological data.

The 127 ha (310-acre) scheme will take its inspiration from the Knepp wilding, and will stretch along the line from the viaduct at Denham Country Park to the Chiltern tunnel's southern portal.

[293] Early proposals for HS2 outlined the construction of a two-kilometre-long (1.2 mi) link between HS2 and HS1, which would have allowed high-speed trains to operate directly from the North and Midlands to destinations in continental Europe via the Channel Tunnel.

[297][298] Following the cancellation of this link, it was proposed that passengers would transfer between these two lines via shuttle bus, automated people mover or an "enhanced walking route" between Euston and St Pancras stations.

In December 2011, it published a study that outlined a case for extending high-speed rail to Scotland, proposing a route north from Manchester to Edinburgh and Glasgow as well as an extension to Newcastle upon Tyne.