Berks and Hants Extension Railway share Call 1861
In 1844, the GWR proposed a 7 ft (2,134 mm)broad gauge branch line from Pangbourne railway station to Newbury while the LSWR was promoting an alternative 4 ft 8 1⁄2 in (1,435 mm) standard gauge branch from Basingstoke to Newbury and Swindon, the heart of GWR territory. However, the following year saw an Act of Parliament passed to allow the construction of the GWR-backed nominally independent Berks and Hants Railway from Reading to both Basingstoke and Hungerford. The capital for this company was put forward in the names of GWR directors, and the following year a new Act of Parliament saw the Berks and Hants formally absorbed into the larger company.
The first section to open was that to Hungerford on 21 December 1847. The line to Basingstoke left the Hungerford line at Southcote Junction on the outskirts of Reading, and was opened nearly a year later on 1 November 1848.
The Berks and Hants Extension Railway (another nominally independent company) was opened from Hungerford to Devizes on 11 November 1862. This formed part of a GWR scheme to provide a more direct line from London to Exeter in Devon;
A third rail was laid along the Basingstoke branch on 22 December 1856. This mixed gauge was to allow standard gauge goods trains to run through from the Midlands to ports on the South coast. Broad gauge trains stopped running on this route from 1 April 1869.
On 27 June 1874, a special road coach service was instigated between Hungerford and Devizes while the engineers converted the single track on this section to standard gauge. The remainder of the line from Hungerford to Southcote Junction at Reading was worked as a single line with trains in both directions using the normal eastbound line with a passing place kept at Newbury while the westbound line was converted. The last broad gauge train ran on 30 June and the following day the trains started to use the new standard gauge westbound line and ran through to Devizes again. Conversion of the eastbound line could then take place, and a normal service resumed on 4 July.
At Devizes the Extension Railway connected with a branch line from Holt Junction on the Wilts, Somerset and Weymouth line which allowed through trains over the Berks and Hants to Bristol Temple Meads. The Stert and Westbury Railway was opened on 29 July 1900, (1 October 1900 for passengers) from a new station called Patney and Chirton to Westbury which allowed a shorter journey via Hungerford to Weymouth from where passengers could sail to the Channel Islands. From 2 July 1906 through passenger trains on the Reading to Taunton line started running over the Berks and Hants line following the completion of a new cut-off line from Castle Cary railway station to Cogload Junction near Taunton.