UK Visitor visa question after refusal of entry

[hhhleanne]

Does anyone know if there is such a thing of a 'stop indicator' and if this is removed after a successful application for a visitor visa after a refusal at border?

Basically a commonwealth citizen had issues entering (rationale: no ties to their country) and was refused entry to the UK a couple of years ago (No ban).
They applied and got a visitor visa successfully around 6 months later and would now like to visit the UK again, my question is, do they still need to get prior clearance by getting a visitor visa or by gaining one previously would the alert/stops and checks (stop indicator) be removed from the system and they shouldn't face further interrogation from now on?

Thanks!