A woman’s desperation to protect her three grandchildren from a predatory paedophile has led to her being threatened with prosecution for keeping them out of school.

The grandmother claims the children – the youngest aged just six – have been “groomed” by her daughter’s sex-offender ex-boyfriend and is refusing to let them leave the house alone.

She stepped in to look after the youngsters because of their mother’s alcohol and drugs problem and says she lives in permanent fear that the paedophile – only recently released from prison after sexually assaulting a young child – will target them.

Now she is bidding to convince three Appeal Court judges that Islington Council – which has written to her threatening prosecution if she doesn’t send the children to school – is unreasonably refusing to recognise the severe risk of abuse.

Her barrister, Ian Wise QC, told the court that her ultimate objective is to make the council move her and the children to a secret address outside the borough where they can be safe.

But town hall officials insists that the grandmother’s concerns are over-blown and social workers say the children are at “no greater risk than any other child in the borough”.

The court heard the paedophile is shortly due to move out of a bail hostel and the grandmother is not convinced her daughter’s relationship with him is over.

Describing him as “a very high risk” to the children, Mr Wise said he had systematically preyed on youngsters within relationships.

The barrister said Islington’s stance was “irrational” and accused the council of failing to put into place a “realistic plan of action”.

However, Bryan McGuire QC, for Islington, insisted the case had been given “intense scrutiny”.

He said social workers recognised that any mistake could result in the children being sexually abused but that their assessment of the risk was “sound”.

Mr Wise told the court that the children had no contact with their mother over the Christmas period.

Lords Justice Thorpe and Longmore and Lady Justice Black reserved their decision.