Hi Barry - only hi-po C3's and BB cars had the rear anti-roll bars as standard - I believe later C3's may had them as standard. When you look how 'insignificant' the links from the ends of the ARB to the chassis are you might question the effectiveness - especially if you have other options to improve handling (like wider low profile rubber)
When you go round a corner hard one side of the suspension is in tension and the other side is in compression, the ARB is there to try and equal out the forces to maintain the full contact patch on the side that is in tension
ARBs are especially needed with (not slow) vehicles with a high Centre of gravity
When the Range Rover Sport first came out, it was superior to the previous models in terms of less body roll - but was frequently wearing out the ARB bushes due to a heavy load made worse by the high centre of gravity - the fact that the bushes were wearing shows the links were doing the job.
You would not want to taz one around the lanes without an ARB - I nearly wrote an early RR off trying to swerve round a pigeon - the body and chassis were both swerving but not in unison so when you applied opposite lock the body was still going the oppposite way and so on and so on - lucky nothing coming the other way I was on both sides of the road trying to get it straight.
