Brecon & Merthyr Tydfil Junction Railway dividend warrant 1880
The Brecon & Merthyr Tydfil Railway was incorporated by two Acts of Parliament dated 1 August 1859 and 15 May 1860, to build a railway between the Vale of Usk and the Taff Fechan. It was hoped that by superseding the Brecon & Abergavenny Canal and Brinore Tramroad by the railway, agricultural produce from Brecknock would find better markets in Merthyr and Dowlais, and the cost of iron, coal and lime would be greatly reduced in Brecknock.
Before construction began disputes arose with the Mid Wales Railway and Hereford, Hay & Brecon Railway about the acquisition of the Hay Railway (a horse worked tramroad), as all three companies wished to use its alignment to gain access to Brecon.. Eventually it was agreed that the B&MR should acquire the section between Talyllyn Junction and Brecon, and the MWR the section between Three Cocks Junction and Talyllyn, confirmed by Amendment Acts of 1861. The HH&BR who had originally purchased the Hay Railway on 6 August 1860 for conversion, was left with the remainder.
The first B&MR passenger train entered Brecon from Pant (near Dowlais) on 1 May 1863 to a temporary terminus at the Watton. The MWR commenced goods and passenger services on 21 September 1864, closely followed by those of the HH&BR. An Act to amalgamate the B&MR with the HH&BR was granted on 5 July 1865, but an investigation into B&MR affairs following the financial crisis of 1866, revealed that the preferential share holders had not ratified this decision, so the two companies resumed their separate identities by means of the B&M Agreement Act of 1868.
The B&MR opened a new station at Free Street Brecon on 1st March 1871 for joint use. They and the HH&BR used it from this date and the MWR did so from 1 May, transferring from Mount Street (Neath & Brecon Rly) where they had been since moving from the Watton on 22 October 1868. The N&BR did not agree to extend its trains to Free Street until 1874.
The B&MR now promoted various acts which would enable it to build its own lines to Newport, Cardiff and Nantybwch. At this last point it wished to connect with the Merthyr, Tredegar and Abergavenny Railway to prevent its westward expansion. The B&MR was only successful in reaching Newport, which it did by obtaining its Bargoed Rhymney Branch Act, and purchasing the Rumney Tramroad for conversion into a railway. The Taff Vale Railway was successful in obtaining a restrictive clause in the Bargoed Rhymney Act which forbade the B&MR from opening these lines until its original line to Merthyr was completed. The Merthyr Branch was opened to Cefn on 1 August 1867 following the completion of the Cefn Coed Viaduct, and passenger trains finally reached Merthyr High Street station on 1 August 1868. The B&MR then lost no time in starting its Brecon to Newport services, which commenced one month later on 1 September 1868.
The B&MR opened a short branch from Pant to Dowlais on 23 June 1869, which after 1 January 1873 when the westward expansion of the Merthyr Tredegar & Abergavenny Railway had reached Penywern and Ivor Junction's, became the terminus of London & North Western Railway services from Abergavenny. After the LNWR threatened to build its own line into Merthyr, the B&MR agreed to make most of its Merthyr branch a joint with the LNWR, and in return the LNWR paid the B&MR half the original construction costs. Accordingly the LNWR built a connecting line to Morlais Junction near Vaynor, and LNWR passenger trains entered Merthyr High Street Station on 1 June 1879.
The B&MR was absorbed into the Great Western Railway in 1922 under the Railways Act of 1921