2.2 For agents only: accepting instructions from a landlord
2.2.8 Using subagents
Agents who want to appoint a subagent must first obtain the landlord’s authorisation. Appointing a subagent without authorisation may be considered a breach of duty unless it is contained within the agent’s terms of engagement.
This comes from the Law of Agency. An agent has a very powerful position as you are legally entitled to make a contract on behalf of someone else.
Because of this, only the person (or organisation) specifically authorised by the landlord to act on his behalf as agent will be entitled to do so. Passing the work on to someone else to do will be a breach of your duty as agent.
Because that other person has not been approved by the landlord, to enter into contracts on his behalf – something which could have huge significance for him.
So if you do want to pass this work on to another agency or organisation, you need to have the landlord’s specific approval to this, in writing.