third party holding a deposit

Other

we are a letting agent. we let a property 3 years ago, tenant find only. the tenant requested we hold the deposit rather than give it to the landlord and at the time the landlord agreed.
now the tenancy is coming to an end and the landlord is asking for the deposit. the tenant has insisted that we do not pass the deposit over and that at the end of the tenancy the landlord carries out an inspection and they agree if there are any deductions.
we are caught in the middle, my personal opinion is to hold the deposit until the two of them reach an agreement, any advice on the legal position. the deposit was not lodged ion TDS as the tenancy started well before this legislation.