Evict family member

Hi,

I would be ever grateful, if you can kindly shed some light into the following query:-

Some Background:

• I am a landlord, and currently renting my property to my brother
• My brother, and I signed 18 months Assured Shorthold Tenancy lease agreement
• I’ve also allowed his family to live with him, but they are NOT party to the lease agreement
• The rent is paid at the end of each calendar month, and is always up-to-date
• His Tenancy ended in 1st/July/2019, and neither party renewal the lease agreement
• Since, August/2020, my brother & his wife encountered some marital problems
• As a result, he decided to move out, leaving his wife + children occupying the property
• He still pays the full rent on time, and has never defaulted
• I have asked my brother to surrender my property, as he NO longer lives there, but NO joy

My Questions:

1. Has my brother violated his tenancy agreement by moving out, yet allowing ONLY his family to occupy my property, WITHOUT my consent?
2. Has the tenancy agreement AUTOMATICALLY turned into a PERIODIC AGREEMENT, since it was not renewed?
3. I really need my property back hence, how can I LAWFULLY RECLAIM my property?
4. Do I need to take a LEGAL ACTION, or is there ANOTHER WAY?

Any other hints/tips would be much appreciated.

Thank you,

Roger.