Basically it is a GCA without glideslope guidance, (azimuth only), runs down to non precision minima.
Not quite right, I think, though I stand to be corrected. A proper GCA when they were around used a precision approach radar (eg the old Quad radar) with both glideslope and azimuth information allowing the final controller to get you down to ILS type minima as I recall.
The surveillance radar would vector you round into an appropriate position to be handed off to final, who would do the rest.
"You are dangerously below glidepath, I cannot control you further, look ahead and crash visually...!"