The development of Treforest into the modern village of today is due almost entirely to the industrial ambitions and capital of the Crawshay family of Merthyr Tydfil. Their association with Treforest began in 1794 when Richard Crawshay purchased a plot of land at Ynys-pen-llwch on which stood a small mill for the rolling of tinplate. This enterprise with the aid of the Glamorganshire Canal, which opened in 1794 to transport its products, became an immediate success.

Even so, the business languished for a while under the shadow of Cyfarthfa, in which William Crawshay I (1764-1834) had invested the family’s income. Against his father’s wishes William II, tired of waiting to inherit, began to rejuvenate both the tinplate works and the foundries located in Treforest. As William II came into his own as sole owner of the Cyfarthfa empire, he lost interest in the tinplate works at Treforest delegating the completion of the modernising process to his son Francis Crawshay (1811-78).

By 1835 these works were under the direct control of Francis Crawshay who had moved to the Treforest from Hirwaun (where the family owned an ironworks) and now lived at Forest House - the site of the University of South Wales today. The following years saw the expansion and modernisation of the tin works, until they had become the largest in Britain by 1836. During this period the Crawshays had also acquired a small iron works by purchasing adjoining land to their existing land at Treforest. They had expanded to form the Taff Vale ironworks, which in conjunction with the tin works formed the Fforest Works.

The old Taff Vale Iron Works were established in the early 19th century, stopped about 1875 and dismantled a few years later. On the site of those old works, streets such as Lawn Sreet, Lewis Street and Windsor Road were built. When Francis Crawshay owned Treforest ironworks he erected three furnaces built to a height of about 40 feet in 1856. For some years it was owned by Mr Fothergill. The Treforest Tinplate works was open until about the end of the 1920s.

It was the success of these industries and the early link to the Rhondda coal trade provided by Dr Griffith's tram road between Dinas and Treforest, that led to the rapid growth of the village. Treforest was a satellite village which began to grow before Pontypridd, as its location was far more accessible. It looked as if it would outstrip Pontypridd in population and as an industrial and commercial centre. But eventually Treforest began to lose momentum since it did not have any coal mines in its vicinity. Coal mines were situated in Pontypridd itself or close to the Rhondda Valley which meant that it caught up with Treforest and soon overtook it in growth and importance.

Large numbers of workers were attracted to the district and the subsequent rise in population led to an increase in both building activity and trade. Houses were quickly built to accommodate the workers, some of the earliest streets being Long Row, Forest Row, River Row, and Market Street, and shops opened to provide them with the goods they required. Public houses were opened with five being listed in the 1884 Kelly's Trade Directory, including the Ballar's Arms, the Greyhound Inn, and the Danygraig Arms.

The religious needs of the inhabitants were also catered for with the establishment of many non-conformist chapels, some of the earliest being the Libanus Welsh Baptist Chapel (1841) and the Saron Methodist Chapel (1843). Treforest was the first village in the district to have an established post office and any mail from Pontypridd passed to the Treforest Post Office before despatch. It also had one of the earliest markets, with regular markets being held at the Market Square (later known as Castle Square) from at least 1803. Treforest railway station was not opened however until 1847. Today, Treforest is often considered to be simply an offshoot of Pontypridd, mostly noted for its university. However, during the early part of the 19th century, Treforest was unquestionably a livelier place than Pontypridd (or Newbridge as it was then known) with more facilities and a greater potential as a town.

Several buildings were opened in Treforest within a few years at the end of the 1920s and early 1930s. The foundation stone of the Roman Catholic Church of St Dubritius, in Broadway, was laid in 1926. A recreation ground was opened in 1931 and a new Salvation Army Hall the following year. Treforest reading rooms located by the bridge crossing the River Taf and St Dubritius Catholic Church were opened in 1933.

However, in recent years a pattern of demolition has been more frequent including a chimney stack known as the Cymric Foundry that towered above Treforest since approximately 1840 and the Castle Inn Bridge of about 200 years old which began in 2023.

One of the earliest streets in Treforest was Long Row Terrace, shown in this picture c.1977

Francis Crawshay

Francis Crawshay moved into the property in Treforest known as Forest House. The house had been built for his grandfather and stood on the site of a farm, Fforest Isaf (Lower Forest).

Forest House, now owned by the University of South Wales, is a listed building. Externally, it remains as it was in Francis Crawshay's day. However, the grounds of Forest House have seen great changes over the years. In the late 1880s, Barry Railway Company built a line that ran across the land behind the house before entering the Treforest tunnel, which took it on to Pontypridd. The orchards on the hillside below the line disappeared at the beginning of the 20th century as streets including Forest Grove, Bertha Street, and Hilda Street were built.

Forest House

Francis Crawshays' Standing Stones

During his time, Francis Crawshay had erected many isolated standing stones in Forest House's grounds. After his death these were gathered by his brother Henry Crawshay (1812 -1879) and arranged to form a circle of tall stones. These stones were removed, cut up into small pieces to allow them to be used to build road and walls in 1955 to make room for the expansion of Glamorgan Technical College.

After the Crawshay family left Forest House it was owned by a local solicitor named Walter Morgan 1853-1901. He founded the Pontypridd firm of Morgan, Bruce and Nicholas solicitors, which worked closely with the South Wales Miners' Federation. It was from his widow that the house was purchased for the purposes of the South Wales and Monmouthshire School of Mines in 1913. It was at this time that John Calvert's 1845 winding and pumping beam engine was removed here from the Gelliwion Colliery.

The constitution of the school was established under a deed of trust with the earl of Plymouth, Lord Merthyr, and David Davies as the trustees, and George Knox (1869 -1950) was appointed as the principal. It was financed by a levy on the output of the subscribing collieries. This private sponsorship continued until 1928 when the school of mines was placed under the control of Glamorgan Education Authority.

From 1940, the college was known as School of Mines and Technology training young coal workers and army cadets. Despite the change in name, the premises remained very much the same as they were in 1913. The college consisted of four departments and had approximately 150 full-time students and about 800 part-timers. It was the immediate post-war period that saw an expansion and diversification of courses.

The pumping beam engine from Gelliwion Colliery

A number of prefabricated workshops and laboratories were set up and four aluminium classrooms erected behind Forest House. In 1956, the building of a double-storey block near Forest House was completed. The school's success in catering for the growing demand on higher education was reflected in its changing status, progressing quickly from Technical College (1949), to College of Technology (1958), and on to Polytechnic (1970).

In 1967, the first hall of residence was opened on the campus with accommodation for 100 students. At this time there were 632 full-time and approximately 1,500 part-time students. The college's campus continued to expand with the building of a multi-storey building for the department of civil engineering, and later, a building for the students' union, the library, and the department of business. It also offered a range of courses in science and added the first ever Welsh for Adults course in 1967.

The Further and Higher Education Act 1992 allowed Glamorgan Polytechnic to assume university title and corporate status. There was some discussion as to a suitable title for the institution in its new form. Among titles suggested was Crawshay University but some were of the opinion that the name of the ironmaster who had spent so many years at Forest House wasn't suitable, and the title University of Glamorgan was adopted. Sir David Hunt, Secretary of State for Wales on 1 September 1992, performed the official opening ceremony.

In April 2013, University of South Wales was formed following a merger of the University of Glamorgan and the University of Wales, Newport. Since its formation, the University has offered over 500 courses, welcoming students from more than 120 countries which shows how popular the university is with foreign students. The Treforest Campus has a size of 30 acres which is bigger than average university campuses.