Tenancy pre 2007 not put into a deposit scheme?

If the deposit is not in an approved scheme then the tenant can reclaim back 3 x deposit amount I think

My advice would be to just return in full, you don’t want to open a can of worms

Deposit was taken before April 2007 (when schemes started).

However, the Housing Act 2004 rules were changed in 2012 (Localism Act) so that:
Any tenancy deposit still being held on or after 6 April 2012 had to be protected, even if the tenancy started before 2007.

And after the Deregulation Act 2015, landlords had until 23 June 2015 to protect older deposits.

If the landlord still held the deposit at any time after June 2015, he was legally required to protect it.

Your tenancy did become periodic, this is important.
A pre-2007 deposit must be protected when the tenancy became statutory periodic unless returned.

The deposit should have been protected. It wasn’t. Therefore:
– He cannot make deductions
– You can demand the full deposit back
.
Can the landlord withhold the deposit for damage?

Legally no, because:

A. The deposit is non-compliant

A landlord who has not protected a deposit loses all rights to use it for deductions.

B. 2006 inventory is nearly worthless now

And he made changes (doors, boiler) without updating it.
He must prove:

the condition at move-in,

deterioration beyond fair wear and tear,

and actual costs.

He cannot.
So even if the deposit were protected, his evidence is too weak.

Keys returned but landlord charged rent for 3 more weeks

This is usually unlawful unless:

there was a contractual notice period, and

rent was genuinely due, and

the landlord actually needed the period to re-let because the tenant failed to give proper notice.

But you said: “after the keys were handed over to them”

If the landlord accepted the keys, that is usually treated as surrender by operation of law, unless he expressly refused.

Once surrendered, rent stops he cannot charge for a further 3 weeks.

Part of the cost of doing business is getting the property ready for reletting. That cost is not the responsibility of the outgoing tenant unless there is damage above and beyond fair wear and tear.
All fittings in a property have a natural “lifespan” with normal use and that is taken into account when deductions are evaluated. A carpet that is 19 years old plus for example will not be considered to be deductible as it is well past its lifespan.
When you mention the landlord accepting the keys back, had you officially given one months notice and then gave the keys back approx a week later, or did you simply return the keys midway through the month? Had the property been fully cleared and cleaned before returning the keys? Either way, assuming the property was cleared properly, the tenancy end date is a slightly grey area. What was said between you at the time? Did the landlord enter the property early and start work? Technically the tenancy continues after death in the name of the estate until it is lawfully ended in accordance with the tenancy terms, so yes, the full months rent is technically due no matter when you move out. However, if the landlord indicated that he was willing to take the keys back and take possession early (keys put in his hand, rather than through the door), final meter readings taken and utilities switched to landlords from an earlier date – that could indicate the acceptance of an early surrender of the lease by the landlord. A grey area. (I believe the law regarding the end of tenancies following a tenant’s death is changing next year with the introduction of the Renters Rights bill, but that doesn’t help you much).
If the property was left full of the tenant’s unwanted furniture and belongings you need to rethink and offer an amount for the costs in time and rubbish removal the landlord has incurred as your friend’s landlord should be compensated for that.
In your position I would write to the landlord in the first instance and explain that you expect a full refund of the entire deposit and the prorated rent payment for the period after he accepted the return of the keys. You should provide details of who you are, that you are the executor of X’s Estate and the bank details for payment. Set out your legal case for reclaiming the amounts and the time frame you are giving the landlord to comply along with an explanation of the consequences for non-payment.
Your course of action for non-payment is that you will submit a Money Claim Online for both the amounts owed and a punitive amount of 3x the original deposit for failure to protect it.
I don’t suggest you actually follow through with claiming the punitive element because I don’t personally think it ‘fits the crime’, but if everything you’ve said is truthful and accurate (AND the property was fully cleared!) I’m not above a little scare tactic when necessary.Actually claiming the penalty will likely complicate your claim and extend the time involved. Plus it may very well be found to be “time barred”. You have a period of 6 years from the time of the failure to act or the time you should reasonably have been aware of the failure in which to make a claim in most instances, so the amount may not even be awarded.
Sorry this is so long, but it’s a complex issue and I’ve only really scratched the surface.