Yeah, Blue Steel was the last. My Dad was a Vulcan captain flying them, and he was not impressed. Apart from anything else, they took about a whole day to be fuelled (liquids) and to be mated to the Vulcan. This was obviously not sensible.
Having said that, Blue Steel did have an inertial navigation system that could be slaved to the aircraft (Vulcans didn't have such tech until later), though my Dad was fairly unimpressed by its capabilities.
I grew up at the northern end of Woomera test range (largest land based missile test range on planet) and went into geophysical exploration - my father and his crowd would find 'lost' missile shells in the Tanami desert and surrounds, I found a few with remote sensing some years on.
We still have manuals for a few missiles (during the dev stages) dating back to the 1950s and 60s.
My Dad flew a Vulcan from the UK to Woomera with a Blue Streak (never deployed UK
missile) stage for testing in the capacious bomb bay. All sorts of adventures including illegally overflying Indonesian airspace - but the Indonesians could never intercept a Vulcan.
The Len Beadell network is epic.
That's going back a way in time.
EDIT: Not replaced by the Skybolt .. that was proposed, developed, never successful .. the UK ended up going with the US UGM-27 Polaris missile after Blue Steel.