Just as an update on this, the tenant is now looking for somewhere else to rent and has informed my friend that an estate agent will be in contact with her! Obviously, this lodger wants my friend to give a good account of her. I've advised her not to go down that route given the trouble this lodger has caused. However, my friend believes this is her chance to get rid of her for good!
My friend was also advised to put up a security camera pointing towards the front door so that she can see if this lodger is still bringing in children and the pets when my friend is not there. Does anyone know if there are particular rules around having a security camera on her house. She has every intention of telling the tenant that she would be installing this but is concerned about the data protection act. Would she need to put a notice up that she has installed the camera?