Tenant has gone to prison, termiination

Tenancy Deposits

I am having a difficulty obtaining payment of a deposit bond from my local council. The tenant has been committed to prison for 44 weeks and therefore has effectively abandoned the property, his parents have cleared his personal possessions and I now wish to claim for damages against the bond. The Council contend that as the tenancy has not formally ended they cannot pay. They suggest I should seek a possession order, which would cost £355 + for court fees, and delay. As the bond is £450 this seems nonsense and defeats the purpose of the bond. My view is that if the bond were cash in a deposit scheme I could legitimately claim the deposit. Please advise