Top-performing independent schools may be excused from regular inspections in the same way as their state-funded counterparts, The TES has learned.

Ministers and their officials are considering making the change following representations from the Headmasters’ and Headmistresses’ Conference (HMC), which argues it would be unfair for the best of the 250 leading private schools it represents to be treated any differently.

In a letter to Education Secretary Michael Gove the organisation writes: “Many HMC schools are consistently graded ‘outstanding’.

“It would appear anomalous to us if the state ceased to inspect those outstanding schools it funds and for which it is responsible, while continuing to insist on frequent inspection of schools for which it has no such responsibility.”

Mr Gove confirmed in May that he would go ahead with a pre-election pledge to exempt the one in six state schools in England rated “outstanding” by Ofsted from the regular inspection cycle. Under his plan they will be monitored and subjected to inspection if certain indicators “flash danger”.

Now his officials are working out how the same idea could be applied to independent schools that received the best inspection reports. They are looking at the entire sector - HMC and other “association” schools that come under the Independent Schools Inspectorate (ISI), as well as “non-association” independent schools inspected by Ofsted.

The difficulty is the lack of grades directly comparable to those given to state schools by Ofsted. The ISI reports do not issue grades - it uses language that could be interpreted as matching particular Ofsted grades, but it is not uniform.

St Albans School, headed by HMC chairman Andrew Grant, was inspected last year and described as providing an “outstanding educational experience”.

Eton College, inspected this year, received a similar verdict but was described as providing an “education of exceptional quality”.

Ofsted inspection reports on non-association independents - smaller religious or family-run schools - are different again. These are given grades of “outstanding”, “good”, “satisfactory” or “inadequate” but, unlike Ofsted state school reports, there is no single rating for overall effectiveness.

However, they are graded for the overall quality of education, and on this basis 13 per cent of independent schools inspected by Ofsted in 200809 were “outstanding”.

Geoff Lucas, HMC secretary, said he thought another concern of the Department for Education (DfE) was that there was not the same level of data in the independent sector available to carry out monitoring between inspections as there was for state schools. But he countered that levels of parental satisfaction would act as more of a trigger for improvement in independent schools and said it would be “bizarre” if they were left out of the inspection changes.

A DfE spokesman said: “No decision has been taken on future inspection plans for independent schools.”