A survey of 118 local authorities by the Association of Directors of Children's Services found that 35,487 children and young people were recorded as being home schooled on 5 October 2017. Extrapolated across the country this would mean around 45,712 are being home schooled in England, an increase of 21 per cent since 21 January 2016.
More than a third of councils surveyed (37 per cent) said they were aware that home-schooled children in their area were attending unregistered schools and tuition centres, raising concerns that children may be at risk of harm, radicalisation and poor-quality education.
Councils also said they are concerned that because home educators do not have to register with them, the true number of home-schooled children may be far larger.
Despite the growing use of home schooling, the survey found that the average council has just one full-time equivalent worker charged with co-ordinating and monitoring home schooling in their area.
In response to the findings the ADCS has called for families who choose to home school their children to be required to register with their local authority and for councils to be given the power to enter premises to ensure children are getting a good education. Currently, parents are not required to register and councils can only enter premises if they have concerns about a child's safety.
ADCS has also called for additional funding to help local authorities establish systems and safeguards to ensure children and young people who are home schooled are safeguarded and get a good education.
In its report on the survey, the ADCS said: "Many [councils] noted the absence of a registration requirement hinders the fulfillment of local authorities' statutory duties to identify children who are not receiving a suitable full-time education and to safeguard them."
"The growing complexity of this cohort's needs, links with unregistered schools and apparent breakdowns in the relationship between schools and families were also raised as issues multiple times," it added.
Councils reported that home educators cite dissatisfaction with their child's school as the primary reason why they elect to home school and that 76 per cent of home-schooling families accept visits from the local authorities.
The ADCS's call for tighter regulation of home-schooling follows similar calls by both the Local Government Association and Ofsted. Last year a report by Ofsted found children were being taught by unqualified teachers in poor conditions in 150 unregistered schools in England. The inspectorate blamed "professional incompetence and insufficient resources" within councils for a failure to address the problem.
The government has said it intends to take action on unregistered schools but it has yet to respond to a consultation on the matter that concluded in January 2016, prior to Theresa May becoming Prime Minister.