The deaths of 24 men who were killed during its construction are commemorated in Otley churchyard by a monument that is a replica of the tunnel's north portal.

Thousands of navvies lived locally in temporary bothies with their families, and worked in dangerous and wet conditions to facilitate the grand opening in 1849.

Among the several major obstacles on the route was the ridge between Airedale and Wharfedale requiring a long tunnel between Horsforth and Arthington under Bramhope village.

[7][5] Water was taken at first from the town well opposite St Giles' Church, but the excessive demand diminished the supply and spoiled its quality.

At a shareholders meeting in September 1848 it was reported that only 100 yards of new ground were left to be penetrated and Bray stated it would be possible to run a locomotive through the tunnel in the following May.

[13] Two sighting towers were built at a cost of £140[3] for the surveyors to keep the line true, then from 20 October 1845 twenty shafts were sunk to enable tunnelling.

Each day around 2150 wagon loads of rock and earth was removed from the workings to be tipped on the Wharfe embankment leading to the Arthington Viaduct.

For four years the workmen, some of whom brought their families, lived in 300 temporary wooden bothies either in a field alongside the offices and workshops, opposite the cemetery, or elsewhere along the line of the tunnel.

[15][16] There were originally 30 children but their number increased fourfold, and with a grant of £100 from the railway company the school building was enlarged to accommodate them.

[5] Many navvies had been farm labourers from the Yorkshire Dales, North East England and the Fens, or had come for work from Scotland and Ireland.

[14] One of the two sighting towers, a tall, cylindrical sandstone structure, two metres in diameter with four vertical slits near the top and flat coping stones is still standing in the field opposite Bramhope cemetery.

One of the tips is in an area around the scout hut north of Otley Road through to the Knoll, another is south of Breary Lane, one is in a field opposite the cemetery and another near None Go Bye Farm.

[20] During the Railway Mania period in which the tunnel was constructed, the powerful landowners often had a strong influence on the railways being built on their land, and it was due to the demands of William Rhodes of the adjoining Bramhope and Creskeld Halls that the north portal is to an intricate Gothic revival castellated design; it was not simply an entrance and exit for trains, but a fantasy medieval gatehouse garden feature.

Its crenellated parapet has a carved cartouche in the centre featuring a wheatsheaf, fleece and fish[6] – the heraldic device of the Leeds and Thirsk Railway.

[8] Major repair work was done in 2003 and 2006, when the Victorian drainage culvert was replaced and the track lowered to allow access for larger passenger and freight stock at a cost of £10 million.

[26] Records of death and injury were kept from 1847 to 1849, and grants were made to the Leeds Infirmary and a special sprung handcart was provided to transport the injured to hospital.

The 24 men who died are commemorated in Otley churchyard by a Grade II listed monument in the shape of the north portal.

[3] The sadness of the harsh conditions of those days is captured by the simple epitaph on the gravestone of James Myers who is buried in the Methodist Cemetery at Yeadon behind the Town Hall.