The outgoing principal of a Norfolk college has called for a new inspection regime where schools are only assessed for meeting a minimum standard, after criticising Ofsted for the 'destructive' nature of the current system.

Melvyn Roffe, who leaves Wymondham College this month to become head of a private school in Edinburgh, said the regulator currently strikes terror into the hearts of teachers across the county for fear their schools will end up being held accountable for things which they have no control over.

He stressed that if schools are failing children, they should be held to account – but said the current regime encouraged leaders to focus on teaching to Ofsted guidelines, rather than pursuing overall excellence.

Rather than an overall judgement of inadequate, satisfactory, good or outstanding, he said: 'It should be about setting minimum standards and then commenting on how much better than the minimum standard you are.

'That encourages schools to be innovative, to not fall below the minimum standard, but have the confidence to do different.'

However, a spokesman for Ofsted said: 'Far from rewarding schools for conforming, Ofsted wants to see schools and their leaders exercise their powers and use their professionalism to ensure children do well in all aspects of school life.'

Mr Roffe said: 'My criticism is with the whole structure. The destructive nature of the process really hasn't been commented on enough.

'Where schools are not doing well for children, they should be held to account. However, Ofsted's frameworks encourage people to teach to the test.

'When we have had Ofsted here, we've always said they'll come and see what they see and that if they disagree, we'll have a professional conversation about it. However, if you are a school which is operating in a more challenging environment and if you have more things you are not in control of, then I think the terror is the sense of being held accountable for things you have no control of.' He also said inspectors' judgements were 'subjective' but 'presented as some great truth', adding: 'I think it would be much better if we had a bit more humility from Ofsted.'

In his address at Wymondham College's speech day last week, Mr Roffe said: 'Education is increasingly standardised and risk averse.

'We are judged by an inspection regime which rewards conformity rather than excellence.'

He added that the ability to 'do different' was what helped schools 'achieve success that is not shallow or temporary, not achieved by glitzy PR or fiddling the figures – it is success that is real, solid, deep-rooted, wide-ranging and long-lasting.'

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