Tenants Possessions

Other

I rent my house to university students.
I had a tenant whose contract ceased as at 30th June 2014. He has not paid rent for April, May & June nor has he paid his share of the gas and electricity bills - there were 3 tenants sharing the property.
He left the property as at 30th June but did not clear his room. Since then he has partially cleared his possessions but despite constant reminders by e mail and text messages the remainder of his possessions remain in the house. I have put all the remaining possessions together including a TV and stored them in the house in a dry and secure area. He has been advised of this and asked to make arrangements to collect. He has not done so. He still has keys for the house despite being requested to return them. What is my position regarding the disposal of his possessions if he does not collect them within a further reasonable period? There are new tenants in the house since 1st July.
Look forward to your reply.