The teacher, John Ward, successfully fought a decision by social services to stop paying for a taxi to take Jonny and his brother the 14 miles to school from their home on the other side of Scarborough.
Mr Hoyle, in foster care from the age of 12, said: "I know a lot of people who were moved from school to school when they were in care, and as a result got no GCSEs."
Now 20, Mr Hoyle works for the charity A National Voice, which campaigns for looked-after children. His brother Chris is studying physics at university.
Mr Ward,who is now assistant head of Filey school, said: "The biggest problem for teachers is lack of time to do things properly. Schools must recognise that the issue of how to deal with children in care is growing, and make sure they find the time and the staff to address it."
Mr Ward said as soon as he found out that Jonny's taxi was going to be withdrawn, the school reacted immediately and made sure its concerns were followed up.