The earliest recorded owners of the Gnoll Estate, given as a gift by Queen Elizabeth I, were the Earls of Pembroke.
The Evans family of Neath make the customary claim to be descended from Iestyn Ap Gwrgan who is known as the last prince of Morgannwg (which encompassed the traditional counties of Glamorgan and Monmouthsire).
The first member of the family to make a more convincing figure was Evan Yr Halen (Evan the Salt), a 16th century salt merchant and one of the richest men in the area, his grandson, David Evans lived in Neath and became the High Sheriff of Glamorgan.
David Evans originally leased the Gnoll from the Earl of Pembroke for a sum of £20. The Evans family were described as 'of the Gnoll' by others and the Gnoll Estate was eventually bought by the family in 1658.
David Evans’ son Thomas Evans also lived in Neath in 1600's owning a house on Water Street, Neath, in 1658 he leased the Gnoll from his nephew Sir Herbert Evans 'of the Gnoll' and it was a condition of the lease that he build a new house there.Therefore the gentry hall-house was built at the Gnoll by the Evans family and became the first of the properties which eventually turned into the Gnoll mansion.
Sir Herbert Evans' heiress, his daughter Mary Evans married a Sir Humphrey Mackworth in 1686. Sir Humphrey Mackworth was a budding entrepreneur who established a variety of industrial enterprises in the area and by the end of the 17th century the Mackworth works were the best known in the country.
Sir Humphrey exploited the rich resources of the area and by 1702 mills and furnaces had been established. The mills at the Gnoll included:
- A double and single battery mill which made brass battery and kettles.
- A mill for rolling iron and brass making 'black latern' (thin plates or sheets).
- A mill to manufacture brass wire.
- Several workhouses for swadering, turning, lantering & finishing (soldering kettles & shining them).
- Also several work houses existed for the workers and their families.
The success of the Mackworth enterprises brought with it great wealth and led to Gnoll House being extended and formal gardens being created.
Sir Humphrey was succeeded by his son Herbert Mackworth who saw the next extension of the house in 1730. He had 28 men working to beautify the gardens, at this time a major vista was created and formal cascades were built in Fishpond Wood.
Through the 1740's natural cascades were created in Mosshouse Woods over a mile away from Gnoll house. And through time the grotto, mock castellated temple, gate house and Ivy Tower were also built on the estate.
Herbert Mackworth was succeeded by his son Sir Herbert Mackworth who built a much grander house between 1776 - 78 to match his financial status. He added north and south wings to create the impression of castle towers.
Sir Herbert Mackworth was succeeded by Sir Robert Mackworth in 1791. He married a Mary Ann in 1792 at the tender age of 16 years old. But only two years later Sir Robert Mackworth died age 30 years old.
The beginning of the end