I wouldn't say there's no such thing, because I am sure it has been tried on before by a letting agent, but it seems unusual. There seems no need for the agent to confirm anything to the landlord once you have handed over the cash, he should be giving you a contract to sign and giving you the keys at that point, unless there is some other reason to prevent it (such as you asking for the lease not to commence until a later date). Make sure you obtain a receipt from the agent, or have the agent sign something stating what monies he has received from you, how much of it is for the deposit and how much is for the rent.
Is this agent part of a large company or is he a one man band?
