Peicing together the information which has been made available from various sources I think the sequence of events went something like this:
The teenage girl was out in the city center with her older sister. She had been drinking. Something happened and the older sister became concerned but was unable to get hold of her parents so she called the police. The police were made aware, either at the time the sister called them or when they arrived, that the 16 had autism.
The police attended and took the 16 year old home and, presumably, her older sister too as she appears to be in the video footage.
The mother takes her daughter into the house and is walking upstairs with her when the girl comments that the female police officer looks like her lesbian nana.
The police officer enters the house to arrest the girl for homophobia. This triggers a melt down and in order to make the arrest the officer calls for back up. Several other officers arrive which escalates things further.
The 16 year old is physically removed from the house. The mother makes the police aware that her daughter has scoliosis and the way they are handling her daughter will be painful for her.
The girl was held for 19 hours before being released on bail.
The video is posted on line and the police release a statement saying that the teenager was arrested for making homophobic comments.
The police have reported the family to social services.
This would suggest that there was nothing which happened prior to the girl arriving home which necessitated an arrest otherwise she would have been taken to a police station.
How or why she was in town and had been drinking is not relevant to the reason for the arrest.
Looking like a lesbian is only homophobic if you think being a lesbian is a bad thing.
If I saw a distressed teenager with autism, possibly intoxicated, hiding in a cupboard with 7 police officers trying to arrest her I think I would be be quite vocal in trying to advocate for her too. To say that the mother was shouting and therefore unreasonable is ridiculous, she sounded frightened and desperate to me.
Anyone who thinks the police should be given the benefit of the doubt clearly has not been paying attention to what they've been doing over the last decade. Anyone who wants to find out more should check out We Are Fair Cop and what happens if someone reports you for a hate crime.
https://www.faircop.org.uk/
This is an appalling abuse of power. If an arrestable offence had been committed then there were far better ways for the police to handle it.