Unauthorised pets in rental property?

I have found myself in an interesting situation and would appreciate your thoughts.

In April this year, new tenants moved into one of our rental properties. At the time of application, they advised the letting agent that they expected to remain at the property for one to two years, that they did not have any pets, did not smoke, and that their two adult children would only stay occasionally.

A couple of weeks ago, they served two months’ notice to terminate the tenancy in August, which in itself is not a problem. However, during a recent visit to the property, I discovered that both the son and daughter appear to have been living there on a full-time basis. Again, this is not a particular concern, except that the son has brought two cats into the property.

The Assured Shorthold Tenancy (AST) Agreement clearly states that pets are not permitted without the landlord’s consent, and no such consent has ever been requested or granted. My understanding is that under the Renters’ Rights Act reforms, tenants are expected to seek permission before keeping a pet, which clearly did not happen in this case.

My question is this: if the check-out inspection reveals no visible damage attributable to the cats, would there be any basis for making a deduction from the deposit for specialist carpet cleaning or deodorising, or indeed for the breach of the tenancy agreement itself?

My understanding is that deposit schemes generally require evidence of actual financial loss, but I would welcome your view.

One additional point is that, during two separate conversations (one with me and another in the presence of the letting agent), the tenant stated that she had previously worked as a letting agent, suggesting she was likely familiar with the obligations contained within the tenancy agreement.

I would be grateful for any guidance you can provide.

Thanks,

David