One way gate.

This turnstile leads to the outdoor part of a garden centre. Nice things beckoned.

In my career I’ve passed through turnstiles at eg petrochemical and pharmaceutical plants, prisons and secure units, defence and nuclear establishments. Research laboratories and blood transfusion. Food and drink manufacturing plants. Airports and docks. Vaults. Government complexes during construction or in use. And Westminster and Holyrood Parliaments. Turnstiles at places such as these would usually have a swipe identity card or short life PIN code too. None of that is necessary for the garden centre!