Can a tenancy deposit which was paid pre 2011 be with held

The tenant moved into the flat in 2006 every contract has clearly stated as a clause that it is a none smoking property and no smoking is allowed. The tenant moved out on the 12th August 2016 and every wall and surface is thickly covered in nicotine and the smell is terrible of stale fags. We also have witness statements from work men who have done some repairs saying that the tenant was smoking in front of them in the flat and ash trays full of fags every where in every room ?

It was a 12 month contract which rolled onto another every year but new contracts were signed every year by the tenant to keep records up to date

I changed the agency that look after the properties two years ago and they inspected the property and reminded it was a none smoking property but the tenant still smoked.

I apologise it's not telling me when you reply so I keep having to go back to the beginning.

Is there any more info you need to enable you to advise

he took out the tenancy May 2000 and had periodic contracts to when he left August 2016.
He has asked for his £550 deposit back and if it was just a wear and tear situation of cause he could have it , but we have had the flat assessed and it's going to cost £4000 inc vat to get rid of the nicotine damage and still there is no guarantee we can remove the smell. All his contracts clearly stated it was a none smoking establishment and no smoking was to be done in the property. The flat had its own garden so there really was no excuse . The deposit was not registered as it didn't have to as it was pre 2004 and pre 6 th April 2007 acts , I have had this confirmed by the DPS. All I need to know is has the tenant breached the contract and can I with hold the deposit based upon that . I am having problems logging in so if you could reply via email like you have here I would be grateful . Thanks Jamie

That's fantastic , thank you Jamie