  As we move to an era where next generation low-background particle physics
experiments begin to be designed and constructed, the ability to assay
materials with high sensitivity and at speed with a variety of techniques will
be key. This paper describes the Mirion Technologies (Canberra) specialty
ultra-low background detectors installed and commissioned at the Boulby
Underground Laboratory between 2017 and 2021. The low background levels of the
detectors combine with low background shielding and a radon-reduced dry
nitrogen purge system to give sensitivity approaching the best in the world
without the need for intricate shielding solutions. For an optimised sample
geometry, run for 100 days, it would be possible to reach close to 10
$\mu$Bq/kg ($10^{-12}$ g/g) for background isotopes of interest in neutrinoless
double-beta decay.
