Here's what the Office of Fair Trading has to say about holding deposits: “Where the tenancy does not go ahead because the landlord or agent decides not to proceed, whether this is on the basis of a failed reference check or not, then we take the view that they are not entitled to charge the tenant for the costs they have incurred because it is the landlord/agent who has breached the agreement, not the tenant. If a tenant puts down a holding deposit, provides accurate information about themselves and does not withdraw from the agreement, we see no justification for the landlord/agent seeking to keep any of the tenant's monies on the basis that the landlord/agent decides not to proceed with the tenancy .” Hope this helps.