Letting Agent gone into liquidation without transferring tenants deposit into TDS.

Tenancy Deposits

In June 2008 I used a Letting Agent, lets call it XYZ Estates Ltd, to find a tenant, but self managed by myself. I have documentary evidence of them taking the tenants deposit of £475 and confirmation that it would be transferred into the TDS. Neither the tenant or myself have received any UID code.
The TDS have no record of the letting agent registered with them and no deposits for the property.
Early in 2010 I learned that XYZ Ltd had gone into liquidation. I have since spoken to the Insolvency Practioners who have advised that there will be no funds to distribute to creditors.
The letting agency business and property has been taken over by another company. They have said that it is nothing to do with them.
I have spoken to the previous director of 'XYZ' who has said that the business was sold to the new owners who have subsequently reneged on paying the purchase price as agreed!
As far as I am aware, the liquidators are unaware of this 'sale of the business'.
The previous director of 'XYZ' has also said that the the previously employed Manager of 'XYZ' was responsible for the 'missing' deposits, but had no proof. He added also that the deposits were temporarily placed in a client account with HSBC, which the bank has taken to offset their losses.
Can you advise on my legal responsibilty for the tenants deposit and what action me or my tenant can take to get the deposit back.