Single occupancy AST installs wife and 2 children?

Regarding the tenant, ask for picture ID of the wife and issue a named occupier addendum to the contract. Tell them to keep the noise down if they want to stay beyond the first year, even if you intend not to offer an extension. Tell the neighbour that you've warned them that they won't be renewed if they don't keep the noise down and that you cannot do more (they can complain to the council).

1)
Placate the moaner downstairs
2) Check the wife's right to rent so you are covered
That's all you can do. If downstairs wants to make a noise complaint to the council then so be it. I do not think it will hold much sway
Try not to upset a tenant who is paying

Jasper
As long as your tenant is paying and looking after the property what's the issue.

Your original tenant if a Post Grad should posses a visa giving him 2 years to stay in the country while he studies.
If he goes for a PHD , this will last 3 years .
The visa starts from the day it was approved.
His visa document should give him the right to rent in the UK with his studies

Now you will need access to check the wife's Visa document to see if she and the children have a right to residency in the UK and to what the requirements her Visa documents state for her and the children.
Also see what dates the documents were issued.

As for renting and not wanting Children they come under the Equalities Act 2010 which legally protects people from discrimination.

As for this Tenant downstairs who likes to gripe maybe he has an issue with either the children or maybe a person's colour.
Are the tenants children being disruptive .
Kids are kids

Reply to the comment left by Nick Price at 22/02/2023 - 21:02
Looking at ID/visa documents is no longer sufficient as a right to rent check unless the tenant is a UK national. You now have to ask for a share code and check this on the Gov't website.

Reply to the comment left by Graham Bowcock at 21/02/2023 - 11:47
"Leting on an AST gives the tenant the right to occupy the proeprty as their home. It is difficult for landlords to put (or manage) restrictions on occupation"

Do you actually know this for sure? Legally?
ASTs state who is 'The tenant' and limits occupation to said tenant.

Why do you think that's unenforceable?

Reply to the comment left by Henry Malone at 22/02/2023 - 21:13
Why do you need to know what the issue is? You may be happy with that situation but I would be totally p ssed off if someone lied to me and moved in 3 other people.
If I was faced with a single tenant wanting to take on a property over a pair of tenants who might both being seeing people, I'd pick the single tenant. If I was faced with a pair of sharers vs a family of four I'd pick the sharers. Its pretty obvious that you evaluate potential tenants and pick the one you prefer the most. If they basically mislead you of course you're going to be p1ssed. Especially if it's higher wear and tear. He might have even accepted a slightly lower offer than someone else on the basis that it's a single person.

Reply to the comment left by Cadaceus WHACKWALLOP at 22/02/2023 - 05:32
Is that just pseudo legal opinion?
Is it a clear breach? What's your expertise in that area of law?

Why does noise transmit so easily to downstairs , are the floors bare wood or tiles?
If so I would get carpets down.

Reply to the comment left by Chris Wilby at 25/02/2023 - 08:26
I don't think that's the type of advice the OP looking for. I can't believe most peoples responses to be honest.
The landlord has been conned by the tenant and has 3 unwanted guests living in his flat. I don't think the flooring is the issue!

Anyway, he stated it's a conversion. The floor/ceiling will be suspended timber. Even if it's it's carpeted it'll easily transmit noise if there are young kids running around and making noise.

It is not unusual to let a property to one person only to find that further down the line additional people are living there. Tenants get married, have children, move friends in, and this is almost entirely out of the control of the landlord. People have a right under the ECHR to a 'family life'. It can lead to what we might consider to be overcrowding and it certainly leads to increased wear and tear on our properties, but this is really just part of the business of letting properties.
As others have said, Right to Rent checks are our biggest concern when additional people join the family.
If you are genuinely worried that this family are not suitable for the property, then a sensible approach would be to simply not renew the tenancy at the end of the fixed term, and to serve the correct repossession notices under Section 21, 2 months beforehand.
In relation to discrimination; there are only 9 protected characteristics that Landlords cannot discriminate against, and smoking is not one of them. A refusal to let properties to people with children is discriminatory as a larger proportion of women have children, and gender is one of the protected characteristics.
Similar to 'no smokers' is 'no pets'. Although we now have a responsibility to at least 'consider' a request to keep pets, we do not have to acquiesce if we have a reason. Courts are unlikely to consider 'no smoking' and 'no pets' as a reasonable clause in any AST, but refusing to grant a tenancy, or ending one on this basis would not be unlawful. Ending a tenancy because someone has children is likely to be considered discriminatory, so tread carefully.

Not legally trained.