The selection of its route was controversial, and strong arguments were put forward in favour of alternatives, in some cases avoiding the steep gradients, or connecting more population centres.

Generating financial support for such a long railway was a challenge, and induced the engineer Joseph Locke to make a last-minute change to the route: in the interests of economy and speed of construction, he eliminated a summit tunnel at the expense of steeper gradients.

This involved steep gradients, which Stephenson disliked, and he preferred a route crossing Morecambe Bay by a long barrage, and round the Cumberland coast.

[4][5] He proposed a route passing east of Lancaster and running up the valley of the River Lune past Kirkby Lonsdale.

[6] In 1837 George Stephenson was commissioned by interests in the Whitehaven area to design a route round the coast of Cumberland linking with the Maryport and Carlisle Railway.

[6] Meanwhile Locke revisited his Lune Valley route and proposed a deviation between Tebay and Penrith, involving a shorter tunnel under Orton Scar, before curving to the west through Crosby Ravensworth, Morland and Clifton.

The commission was appointed in November 1839 and had two members, Lt Col Sir Frederic Smith and Peter Barlow, Professor of Mathematics at the Royal Military Academy at Woolwich.

The commission issued a second report in November 1840, which approved Larmer's route, which became the preferred option for a Lancaster to Carlisle line.

The commission stuck to the policy that only one Anglo-Scottish route was viable, but it refrained from any definite recommendation as between west and east coasts.

The line was to strike north from the Lancaster-Penny Street terminus of the Lancaster and Preston Junction Railway and pass round the east side of the town.

[19][16] In early 1845 a petition was received from citizens of Lancaster, asking that the new line should pass to the west of the town, near the navigable section of the River Lune.

[20] The allied railways building the east coast route to Scotland, via Berwick,[note 3] were pressing ahead, and there was serious concern that if the L&CR was not built swiftly, it would suffer a huge competitive disadvantage.

[22][17][23] The Caledonian Railway opened its line from Carlisle northwards to Beattock on 11 September 1847, the first stage of its own construction.

The directors of the L&PJR felt aggrieved that their considerable hard work in negotiation was so casually cast aside, and they all, except one, resigned.

Accordingly the L&CR gave notice of its intention to run trains over the L&PJR when it opened from Lancaster to Kendal, and nobody had the authority to prevent it.

The alarming situation was discussed at a shareholders' general meeting on 4 August 1848, when authority was given to plan an independent line between Lancaster and Preston, as no resolution of the dangerously unsatisfactory status quo seemed imminent.

The subsequent Board of Trade Inquiry report elaborated the entire chaotic situation, and public opinion forced the L&PJR to re-constitute itself.

The NWR opened a line from Morecambe to its own station at Lancaster, Green Ayre in 1848 and was extended eastward to Wennington, joining the uncompleted Skipton to Low Gill route there, on 17 November 1849.

In 1855 there was an upsurge in interest in rival long-distance railways and the idea of continuing to Low Gill, originally authorised but never completed, was revived.

This was obviously a spoiling tactic, and Parliament inserted a clause into the bill requiring the L&CR Ingleton branch to be physically connected to the NWR terminus there.

The LNWR saw that this would abstract far more business than if it permitted the Midland Railway to use its line from Low Gill to Carlisle, on which it could charge tolls on the traffic, and it belatedly offered to concede the facility.

The Midland Railway wished to take advantage of this, which would avoid the expense of constructing the Settle and Carlisle Line, but Parliament refused to allow the abandonment of the project.

A short loop was authorised from Hest Bank to a junction on the Little North Western line at Bare Lane, on the outskirts of Morecambe.

Considerable negotiation on points of detail continued, until from the beginning of 1846 the L&CR determined to have one common station at Carlisle, even if it had to provide all the money itself.

This great leniency of the L&CR over a long and difficult period was probably motivated by the desire that the Caledonian Railway should emerge as a vigorous partner in the Anglo-Scottish trade.

The terms were very generous to L&CR shareholders, as the LNWR feared the line's allegiance might pass to the Midland Railway, which at that time was advancing towards Carlisle from Leeds.

Seizing on this as an excuse, disturbed at what was said to be frequent LNWR domination, and angry that the board would not sanction a lease of the Little North Western Railway, a section of the shareholders led by John Barker, of Milnthorpe, made sweeping charges of defective management causing weak dividends.

A double-track south curve from the Lancaster direction leading to the Hest Bank branch near Bare Lane was authorised by an act of Parliament[which?]

The Lancaster and Carlisle Railway line was a key part of the west coast route from London to Glasgow.

The Preston to Carlisle section of the West Coast Main Line was electrified on the 25kV overhead system; it was energised on 25 March 1974.