The headquarters were at Euston railway station. As traffic increased it was greatly expanded with the opening in 1849 of the Great Hall, designed by Philip Charles Hardwick in classical style. It was 126 ft (38 m) long, 61 ft (19 m) wide and 64 ft (20 m) high and cost £150,000 (equivalent to £14,280,000 in 2016). The station stood on Drummond Street. Further expansion resulted in two additional platforms in the 1870s, and four more in the 1890s, bringing the total to 15.
The LNWR described itself as the Premier Line. This was justified as it included the pioneering Liverpool & Manchester Railway of 1830, and the original LNWR main line linking London, Birmingham and Lancashire had been the first big railway in Britain, opened throughout in 1838. As the largest joint stock company in the United Kingdom, it collected a greater revenue than any other railway company of its era.
On 1 February 1859 the company launched the limited mail service, which was only allowed to take three passenger coaches, one each for Glasgow, Edinburgh and Perth. The Postmaster General was always willing to allow a fourth coach provided the increased weight did not cause time to be lost in running. The train was timed to leave Euston at 20.30 and operated until the GPO instituted its own post train, wholly of Post Office vehicles, in 1885. On 1 October 1873 the first sleeping carriage ran between Euston and Glasgow, attached to the limited mail. It ran three nights a week in each direction. On 1 February 1874 a second carriage was provided and the service ran every night.
In 1860 the company pioneered the use of the water trough designed by John Ramsbottom. It was introduced on a section of level track at Mochdre, between Llandudno Junction and Colwyn Bay.
The company inherited a number of manufacturing facilities from the companies with which it merged, but these were consolidated, and in 1862 locomotive construction and maintenance was done at the Crewe Locomotive Works, carriage building was done at Wolverton and wagon building was concentrated at Earlestown.
At its peak just before World War I, it ran a route mileage of more than 1,500 miles, and employed 111,000 people. In 1913 the company achieved a total revenue of £17,219,060 (equivalent to £1,554,940,000 in 2016) with working expenses of £11,322,164 (equivalent to £1,022,430,000 in 2016).