| Laboratory | BIPM clock code | Clock maker & type | Comment |
| NPL | 1351275 (stopped) | MICROCHIP 5071A/5071B HIGH PERFORMANCE TUBE. | |
| NPL | 1401701 (stopped) | MICROSEMI ACTIVE H-MASER MHM 2010 | |
| NPL | 1401708 (stopped) | MICROSEMI ACTIVE H-MASER MHM 2010 | |
| NPL | 1921701 (stopped) | GROUND-STATE HYPERFINE TRANSITION OF133 Cs | |
| NPL | 1921702 (stopped) | GROUND-STATE HYPERFINE TRANSITION OF133 Cs | |
| NPL | 1353167 | MICROCHIP 5071A/5071B HIGH PERFORMANCE TUBE. | |
| NPL | 1353514 | MICROCHIP 5071A/5071B HIGH PERFORMANCE TUBE. | |
| NPL | 1411004 | T4S iMaser 3000 ACTIVE H-MASER | |
| NPL | 1412011 | MICROSEMI ACTIVE H-MASER MHM 2010 | |
| NPL | 1412050 | MICROSEMI ACTIVE H-MASER MHM 2010 | |
| NPL | 1412153 | MICROSEMI ACTIVE H-MASER MHM 2020 | |
| NPL | 1412157 | MICROSEMI ACTIVE H-MASER MHM 2020 | |
| NPL | 1412158 | MICROSEMI ACTIVE H-MASER MHM 2020 | |
| NPL | 1761703 | OPTICAL TRANSITION 171 Yb+ (octupole) | |
| NPL | 1891701 | OPTICAL TRANSITION 87 Sr | |
