https://machloop.co.uk/
https://www.shootsmart.co.uk/mach-loop-wales/mach-loop/
They list it as in LFA 7(T)
Introduction
“The Mach Loop” is a series of valleys in Wales, U.K. that serves as a military low-flying training area. The official designation is LFA7, Low Flying Area 7. Together the valleys form a circuit in which all kinds of military aircraft and helicopters from multiple nations regularly go to practice their low flying skills. Occasionally, especially in weekends, civilian traffic can also be spotted.
The traffic flow is always counterclockwise and in the north and west, there are several popular locations where people can climb the surrounding mountains to enjoy the show and take pictures in a way that mimics air-to-air photography.