JFZ, true, as long as the stable table remained stable. The mark 1 bombers had the standard G4B system. The Mk 2, which included the BS variants, had the Smiths Military Flight System. This had better flux valves, gyros and interface but when asked how it would fare during an evasive bomb run Smiths said the gyros would precess by no more than 180 degrees.
After the cancellation of TSR2 the Vulcan benefitted from some upgrades to its nav kit. This included a twin-gyro installation - Master Reference Gyros - as part of the Heading Reference System. It was the same MRG that the Lightning used for pitch reference and in the BS Inertial. Its free-gyro drift rate of 0.25 deg/hour coupled with the Decca 72M Doppler then gave performance comparable with contemporary IN platforms. The MFS was relegated to a backup system.