The number of school children contacting Childline because of anxiety has nearly doubled in two years, according to the service’s annual report.

The NSPCC’s counselling service delivered 21,297 sessions to anxious young people in 2017-18, almost double the number recorded in 2015-16.

Just under 13,000 sessions, 5 per cent of the total, related to problems at school like exam stresses, truancy or problems with teachers. Another 7 per cent were about bullying.

“I am not in school today as I am pretending to be ill. I have been bullied every day since I started school and have been having thoughts about ending my own life,” said one pupil quoted in the report.

“I am called fat and ugly and have been told that nobody would care if I died. I feel really sad and want them to stop. Sometimes I think the only way it would all be over is if I killed myself.”

In total, the charity received 278,440 calls last year, of which more than a third were due to mental and emotional health and wellbeing issues.

At least 88 per cent of Childline’s time went to girls, a fact they said reinforced “how they are struggling to cope with growing up in the UK”.

Founder and president Dame Esther Rantzen said the breakdown of extended family networks that provide unconditional support was contributing to unhappiness.

“Families need to ask themselves if there is enough emotional support, whether they’re giving young people enough time,” she said.

“I think that in all kinds of ways the nuclear family has become isolated. It is no longer a priority to keep an extended family together and to use our time and spend our time together.”

Less than one in three young people referred to mental health services receive treatment within 12 months, according to the Children’s Commissioner for England.

Anne Longfield has also called for the government to expand its mental health plans to encompass all schools.

Childline in its report welcomed the plans for more school-based support but raised concerns about their “pace and limited scope”

“Anxiety can be a crippling illness and it is deeply worrying that the number of counselling sessions we are delivering for this issue is rising so quickly,” said Peter Wanless, chief executive of the NSPCC.

“Increasingly Childline is filling the gap left by our public mental health services, providing young people with a place they can go for round the clock help and advice.”