When my husband ws\as young, in the late 50’s-early 60’s, he said you could go right up to the stones. When I first visited in 1983, they were roped off but, you could get quite close. Haven’t gone there in years.
My memory was that we didn’t get too close. But close enough to enjoy the awesome sight. I have a facebook friend who actually works there so she keeps us abreast of everything Stonehenge. Of course, she claims to be a Druid!