How to determine if someone is a lodger or a tenant - England

Hi all,

I'm posting on behalf of someone - we're trying to work out if someone is a lodger or tenant and how we ask them to leave a property. This is in England.

My friend owns and house and she rented out two spare rooms to people from Spareroom. Friend was living in the house at the time, along with her partner and cat. There is no written agreement between them.

Last September, friend and her partner went to Australia. The two renters stayed in the house, along with the cat. Friend kept her room in the house with her belongings in it. That room is locked just to keep things safe. Friend is now coming back from Australia and wants to live in her house with no renters - just her and her partner (and the cat!).

My friend understood the renters to be lodgers but they are saying they are tenants and so need to be given 4 months notice to leave. I have a feeling they may be right - are they?