The range of over the top, ill-informed, inflammatory comments from some posters on this thread is MN at its worst.
OP has done the right thing in informing the school. They should now be investigating using their safeguarding protocol, which would include informing the LADO. The LADO will discuss with the Head and HR whether suspension without prejudice would be appropriate in this case at this point. The investigation will proceed. Interviews follow a protocol. This could all be resolved very early or could turn into something long and drawn out depending on what emerges during the investigation. The Head will keep in touch with the LADO throughout.
It would be best practice to keep a parent updated at least daily- although the school can not reveal details during the investigation.
Parent can report it to the police if they wish. At this point and from the description of the incident, the police (who also work with the LADO) would leave the school to investigate it. Our local police force would visit the Head to inform the school and enquire about the process and keep in touch. In a very serious case (eg an allegation that a teacher punching a student in the face or sexually assaulted them) they would also take immediate action and arrest the teacher.
A school doing this properly with this level of complaint, in the initial investigation, would not have revealed the nature of the complaint/ name of student to the teacher during the first interview. They would have told them a complaint had been made and asked them to describe the lesson - behaviours, any disruption, anything unusual that happened.
Similarly, they would not reveal to students the specifics initially- simply asked them to describe the lesson, behaviours, atmosphere in room, anything unusual that occurred. Students should be interviewed individually and write individual statements- not in pairs or groups.
Often now schools have CCTV which can help enormously in allegations of physical contact.
At this points a clear picture usually emerges and an investigation is either closed down or becomes formal as there is definitely a case to answer- which can then take a while to go through all the processes. The LADO and HR would be advising the school throughout this.
If this was my child I would have asked her to write a detailed account at home asap without me questioning her. It is too late now because once it has been discussed it is no longer uninfluenced. I would write my own account of what she said using her words as I recalled them.
I would keep a note of every communication with the school who I spoke to, what I was told.
I would expect a face to face conversation with the Head about the outcome- and to be taken through an account - without student names- of the investigation and evidence.
Teachers can touch children- appropriately.
The teacher will not be dismissed- even if it went to a tribunal. It is not an offence that warrants dismissal (as it has been described) unless it turns out that there have been other previous substantiated complaints of the same kind and the teacher has not responded to advice, training etc.
A parent can not dictate the sanctions a teacher should face.
Parents should not interfere in the investigation- eg talk to other children or parents or influence their child.
A parent has no right to speak to the teacher about the incident.
Parents who verbally or physically assault the teacher will be reported to the police and can expect an investigation also.
These are awful cases which can drag on for a long time. I have dealt with very complex ones that have literally taken months - with the police involved and a prosecution. They are very stressful for children, parents and teachers.
I have also dealt with ones where they are resolved by the school quite quickly eg the child exaggerated or even lied and the child admits that, there was a misunderstanding (you would not believe how often this happens with words but it would not be the case here), there was a misinterpretation eg a child felt humiliated, a teacher thought it was a joke and did not intend to embarrass, or a teacher put an arm out to stop a child leaving a room but a child interpreted that as a teacher attempting to grab them, or there was an incident but it is minor enough to be dealt with within school and does not require longer investigation but the teacher receives training or supervision and a conversation takes place between school, child, teacher to repair the situation, or a teacher receives a warning and is put on a period of training and an action plan.