Actual settlement is handled by the solicitors and the salesperson is not actively involved.  Once settlement (payment of the balance of the purchase price from the purchaser to the vendor) has taken place, the vendor's solicitor will notify the salesperson that it is complete and clearly instruct the salesperson that access to the property can be made available to the purchaser - normally in the form of handing over the keys.  

The handing over of the keys is an actual legal process as the keys symbolizes the property itself and thus has to be done in person only once the vendor's solicitor has confirmed it may take place. 

If the salesperson can not personally hand over the keys, they must make arrangements with their manager to do so.  Keys can not be left with any other person or under a rock or similar for the purchaser to pick up.  

Once settlement is complete and keys handed to the new owners, the transaction (referred to as deal in the AML Hub), must be marked as "Complete".  The salesperson must please notify the Compliance Manager (via email) that the status can be changed accordingly.