The government has defended its decision to give schools an overall grade as part of its new school report card, despite concerns being raised by a panel of cross-party MPs.
Presenting its response to a Commons schools select committee report this week, the Government said a "summary" score was of "great importance" for parents trying to gauge the performance of a school.
In January, the committee warned the Department for Children, Schools and Families (DCSF) over the need for a single grade, adding that it had been "struck by the weight of evidence" arguing against an overall score.
The report stated: "It is true that Ofsted comes to an overall judgment on a four-point scale, but this judgment is meant to be the result of a very extensive analysis of a school's provision across the board, relying on quantitative and qualitative evidence and first-hand experience of the school at work.
"A school report card is not, and in our view never can be, a full account of a school's performance, yet the inclusion of an overall score suggests that it is."
The DCSF acknowledged there were concerns from stakeholders, but said a single score was integral if the Government was to shift the focus from school league tables.
In its response, the Government said: "Without an overall score, we believe there is an overwhelming danger that public attention will continue to focus on a single indicator - raw academic performance - as summarising a school's overall performance."
It believes this would ignore the different challenges schools face, such as the progress their pupils make, and their contribution to children's wider well-being. "An overall score - or summary statement - will make our priorities clear and visible to all," it said.
The report cards are included in the Children, Schools and Families Bill, which is currently making its way through the House of Lords. The Government admitted there will be "challenges" around how the cards will sit alongside the more holistic Ofsted reports.
Mick Brookes, general secretary of heads' union the NAHT, described the Government's decision to ignore evidence against a single score as "astonishingly arrogant".
"It's quite astounding that this government doesn't listen to anybody - it doesn't even listen to its own parliamentary select committee," Mr Brookes said.
"It's also quite worrying that there is a unanimous professional body of thought that says a single letter or grade will replicate league tables, which is exactly what the secretary of state (Ed Balls) wants.
"It will be grossly unfair. The Government can't say how the weighting will be biased to those schools that are doing the greatest of jobs despite their context."