The mirror makers of Newcastle

Space nebula which looks like a red cloud in a doughnut shape

This image of the Rosetta nebula NGC2237 is complied from data from the Isaac Newton Telescope survey of the Northern Galactic Plane. Credits: Nick Wright/IPHAS collaboration.

Some of the world’s largest and most important telescopes were built here in Newcastle in the 1900s by a company called Grubb Parsons. Even today, astronomers worldwide rely on these ground-breaking observatories.

Giant telescopes use mirrors to collect and focus the light. These mirrors have to be flawless and perfectly aligned for them to work. Grubb Parsons was one of only a few companies in the world with the skill to make the huge mirrors needed for the giant telescopes of the time.

The Isaac Newton Telescope was built by Grubb Parsons and has a 2.5 metre mirror. It started life in England in Herstmonceux in 1965, but was later moved to the Canary Islands because of the better weather. It also received a new mirror.

The Anglo-Australian telescope’s 3.9 metre mirror was ground and polished by Grubb Parsons. It has made many amazing discoveries, including finding streams of stars left over from smaller galaxies that fell into our Milky Way!

The William Herschel Telescope is located in the Canary Islands. It uses a mirror that is 4.2 metres across. At one point it was the third largest optical telescope in the world. It was the last telescope constructed by Grubb Parsons.

Black and white image of a person inspecting a large doughnut shaped mirror that is lying down.

Mirror of the William Herschel Telescope (WHT) in the Grubb Parsons factory.

Remembering a community company

Building telescopes of this size requires an equally large team of people! The Parsons factories were one of the biggest employers on Tyneside in the 1900s. They were an important part of the economic and social life of the North East.

Grubb Parsons had a diverse team. They needed optical engineers, metal workers, joiners, crane operators, and secretaries.

Maureen Sheehan worked for the company from 1962 to 1975. She started as a lab technician and worked her way up to the position of Chief Inspector of Optics. Her job was to make sure every lens and mirror that left the factory was made to the highest standards.

Grubb Parsons and their parent company, CA Parsons, were famous for looking after their employees. Maureen remembers how colleagues fostered a vibrant community spirit. They organised sports competitions, dinner dances, and festive parties. The company also organised clubs like gardening and darts for its workforce.

Did you know... 

The first calculator bought for Grubb Parsons cost £400 in the early 1970s! Before that they performed detailed calculations with slide rules. Their first computer took up an entire room in the factory!

Relevance today

Although they are no longer among the world’s biggest telescopes, the Isaac Newton Telescope, Anglo-Australian Telescope and William Herschel Telescope are still used by astronomers

Large and white telescope dome attached to a two-story building, situated on a mountain above the clouds.

Dome of the William Herschel Telescope at the Roque de los Muchachos Observatory, La Palma. Credit: H. Raab

Related artefacts

Concave mirror.

Grubb Parsons concave mirror

During World War 2 many manufacturers switched to helping the war effort. This coated mirror was crafted by the Grubb Parsons factory. It was probably used on a searchlight.

Location: TWAM

Model of the Isaac Newton Telescope

The mirror in the Isaac Newton Telescope (INT) was manufactured by Grubb Parsons in the 1950s. This involves grinding down a glass “mirror blank” into a precise shape, which is then coated to make the mirror.

The INT was situated at Herstmonceux Castle in Sussex. It was later sent to La Palma in the Canary Islands, with a new, higher quality mirror.

Location: TWAM
TWCMS : 2001.5143

Front of a leaflet entitled "Two Fathers and Two Sons". Four headshots of men are also shown.

Booklet by the Reyrolle Parsons Group entitled Two Fathers and Two Sons

 This small publication details the work of Thomas Grubb, William Parsons, Sir Howard Grubb and Sir Charles Parsons related to astronomy, optics and engineering. 

Location: TWAM
TWCMS : 2013.1278