The sacking of a teacher who allowed pupils to use a sledge on school grounds will leave others afraid to innovate and experiment in future, a teaching union has warned.

Richard Tremelling was dismissed from Cefn Hengoed Community School in Swansea after allowing two of his Year 11 GCSE pupils to use a sledge during the snowfall of February 2009.

This week, Mr Tremelling was reprimanded by a General Teaching Council for Wales (GTCW) disciplinary panel after being found guilty of unacceptable professional conduct.

However, he was cleared of charges of not making a risk assessment and not following health and safety guidelines, and an independent investigation found that there was no risk of harm to the pupils.

Colin Adkins, representing Mr Tremelling on behalf of teaching union the NASUWT, told TES Cymru the case would have clear repercussions for the profession.

“Teachers won’t try to innovate or experiment to enthuse pupils any more because they will worry about the consequences,” he said. “They are going to take a very conservative approach, play by the book and teach the curriculum to the letter. You will be left with a very stale learning environment.”

Chris Keates, the union’s general secretary, said: “It’s important that schools take health and safety seriously - it’s in the best interests of staff and pupils that there is a safe working environment. But, like all regulations, they need to be grounded with a balanced approach and common sense.”

Mr Tremelling, who was head of Cefn Hengoed’s design and technology department, told the hearing he took the sledge into school to demonstrate design and technology principles and reinforce prior learning.

The 30-year-old sledge was made from wood, plastic and metal and had a seat, steering wheel and brakes.

He said: “This wasn’t a cheap pound;10 sledge from Asda. I took in a classic Scandinavian-designed sledge with safety features.”

After quizzing his pupils on the design features of the sledge, Mr Tremelling agreed to allow two boys to test it during morning break.

He said he made a “thorough and comprehensive mental risk assessment” before allowing the boys to use the sledge on a snowy slope at the rear of the school.

“As a qualified and experienced teacher, I know my responsibility to my pupils,” he said. “I would not have continued with the activity had I thought there was a risk of harm.”

He said the 10-minute activity was a “one-off test run” and an extension of his lesson, with “clear learning objectives”.

But Rosa Fernandes, presenting the case on behalf of the GTCW, said headteacher Sue Hollister had previously forbidden pupils from using the snow-covered banks over safety concerns, and had warned staff about the recent sledging- related death of a schoolboy from the north of England.

The panel found Mr Tremelling guilty of allowing pupils to go sledging, not having the headteacher’s permission, ignoring cautionary words of warning from colleagues and denying the allegation when questioned by Mrs Hollister.

However he was cleared of five charges including making no risk assessment, having no parental consent, and not following health and safety guidelines. The reprimand will remain on record for two years but he can continue teaching.

A spokesman for Cefn Hengoed said the school would like to “draw a line under the matter”. “Clearly, the decision to dismiss Mr Tremelling was the right one given the circumstances and his disciplinary record,” he said.

• Original headline: Sledge teacher sacking could curb innovation, warns union