It was intended to convey the mineral products of the Forest of Dean to the ironworks of South Wales, by connecting to the Newport, Abergavenny and Hereford Railway at Little Mill Junction.

The CMU&PR intended to acquire the Monmouth Railway, actually a horse-operated plateway, and convert it to locomotive operation.

A limited goods service was retained for a period at Usk, and it was only the Royal Ordnance Factory at Glascoed that kept part of the CMU&PR system in operation until complete closure in 1993.

It was a north–south trunk route from Hereford, in fact connecting with the Monmouthshire Railway and Canal Company near Pontypool for the final approach to Newport.

[note 1] It was observed that an extensive and productive agricultural region lay nearby, east of the NA&HR route and the idea formed that a line from Monmouth through Raglan and Usk would be advantageous.

A railway line connecting Coleford through Monmouth to Pontypool would be able to convey iron ore and coal to the smelters of South Wales, specifically to Nantyglo.

The ironmaster Crawshay Bailey was a prime mover in bringing the idea to fruition; it took shape as the Coleford, Monmouth, Usk and Pontypool Railway.

[1][2] The proposed railway would, it was claimed, offer the most direct route for the lucrative coal traffic between South Wales and London.

The line could form a junction with the Newport, Abergavenny and Hereford Railway near Little Mill, two miles north of Pontypool Road station.

The railway was to be 22 miles in length, and there was to be a branch at Dixton to give access to Monmouth Gas Works (though this was never built).

Double track would be provided as necessary, no doubt because of the heavy traffic flows foreseen at this stage, in its role as a hoped-for through trunk route.

[note 2][1] The CMU&PR now took stock of the situation; continuing to Coleford would involve converting the Monmouth Railway by relaying the track (which was a plateway), and enlarging its tunnel.

The Monmouth Railway would continue in operation as a plateway, and minerals brought to Wyesham would be transshipped there to wagons on the CMU&PR.

This was considered an important step in improving the local economy, and as Ross-on-Wye was only 8 miles from Monmouth, it appeared a natural initiative to connect the two towns by a railway.

May Hill was at first intended as a temporary station only, while the Ross and Monmouth company completed a bridge over the River Wye.

[1] Local interests put forward the idea of a railway following the lower Wye Valley, and connecting Monmouth to Chepstow, on the River Severn.

This moderately long new line gained considerable support, but the financial depression following the failure of the banking firm of Overend, Gurney and Company in 1866 resulted in a complete inability to raise money for railway schemes, and in 1868 the project was reduced to construction between Monmouth and Coleford only.

A national strike was called by the Associated Society of Locomotive Engineers and Firemen (ASLEF) from 28 May 1955, effective until after the intended closure date of the service.

On 12 October 1957 a special train arranged by the Stephenson Locomotive Society was run over the entire line, on which the track was still serviceable.