A high school principal was yesterday at odds with a bus operator and the county council over the reason why a window fell out of a coach as it took students home.

No children were hurt in the incident, which happened while the bus from Reepham High School was about half full on Tuesday afternoon July 10.

Charles Sanders, managing director of Sanders Coaches which operates the route, said the driver heard a commotion and stopped the bus, and believed the window had come out after a student hit the glass with enough force to push it out of its rubber mould.

Norfolk County Council said it was taking the issue of pupil behaviour up with the school.

However, high school principal Mark Farrar denied a pupil had kicked, punched or smashed the window - and said he was 'very surprised' that the neither the bus company nor the council had contacted the school about what had happened.

Mr Sanders said the missing window did not present a major safety concern because it was at about shoulder height, but the driver moved the remaining passengers to the front of the vehicle before he continuing the journey.

He said buses were designed for passengers who sat safely in their seats, and that similar incidents had happened three or four times before in the past 30 years because of misbehaviour.

Asked what he would say to parents worried about safety, he said: 'If their children are well behaved and sit down, [coaches] are the safest form of transport, and our vehicles are maintained to the highest levels.

'We do our upmost to keep our vehicles 100pc at all times but from time to time you get these little things that happen. They should not happen.'

He said the company would submit a written report to Norfolk County Council and it was up to them whether they took any further action.

A council spokesman said: 'The county council is satisfied this was not due to the condition of the vehicle, or any failure of maintenance, and that the most likely cause was pupil behaviour. This is being taken up with the school.

'As soon as the driver was aware that the window had been knocked out, he moved all the pupils to a safe position at the front of the vehicle. This was only possible because the vehicle was only about half full. If it had been full, it would have had to wait for a replacement vehicle.' Mr Farrar said in a statement: 'We were very surprised to hear that the window fell out of the bus as neither Sanders or the county council contacted us about it.

'Normally they do so if they have any concerns about pupil behaviour.'

Mr Farrar added: 'Once we were made aware of the matter, we carried out a full investigation. It appears that three 13-year-old boys were pushing against each other in a childish but not malevolent manner.

'No-one kicked, punched or smashed a window and the incident has been dealt with.'