What lock for exterior gate to be opened both sides?

[CoolHands]

as title. Have an exterior gate that needs to be locked at all times. But access required from both sides for different tenants. Only a normal garden gate type thing 6ft high though) but will be out in all weathers. Any ideas? I can modify the gate / post as necessary.

this is the gate:

Edited by CoolHands on Friday 29th August 19:00

[CoolHands]

wow that looks pretty good cheers. Haven't seen one like that before.