Based on the design of the Carlos Sanchez Telescope in Tenerife it is a Cassegrain device with a thin primary mirror, around 2/3 thinner than in other contemporary devices and weighing only 6.5 tonnes. The mirror is held in a massive steel 'cell' of 20 tonnes which is linked to the supports by Serrurier trusses. The instrument is held and pointed by a massive 'English Equatorial mounting' or yoke which sits on ball-bearings on steel piers, swinging east-west and rotating around north-south. The mass of the mount limits the telescopes access to objects in the northern sky but it is extremely sturdy and free from deformation and so allows very accurate pointing. The telescope was built between 1975 and 1978, the mechanicals by Dunford Hadfields of Sheffield and the optics by Grubb Parsons of Newcastle. Called the Infrared Flux Collector it began operation in October 1979.
Built as a relatively cheap device it has been extensively upgraded. A program of improvements from 1990 to 1998 have greatly improved the imaging performance.
External link
http://www.jach.hawaii.edu/JACpublic/UKIRT/telescope/telescope.html