Every head teacher of a state secondary school in Surrey has signed a letter to the prime minister expressing their “vehement opposition” to plans for more grammar schools in England, the BBC reports.

The heads say their “unprecedented” coalition reflects the “confusion” caused by plans to increase selection.

They argue that 95% of pupils in Surrey are already at good or outstanding schools.

The government says that providing more grammar school places would give extra opportunities for poorer pupils.

The letter sent to Prime Minister Theresa May and Education Secretary Justine Greening, states that heads in Surrey are strongly opposed to creating a “selective, segregated, two-tier state funded system of education”.

In the ‘hard-hitting’ letter, they accuse ministers of creating “confusion and fragmentation” in England’s school system, with the grammar school proposals based on a “nostalgic and unrealistic vision of society”.

The heads have told the prime minister that the comprehensive system delivers high standards and that this will be undermined by the re-introduction of a grammar system and selection by ability.

“It is impossible to have grammar schools without secondary modern schools or their equivalent,” the letter goes on to state.

The head teachers further argue that less well off pupils are under-represented in grammars and that there is little evidence of any positive impact on social mobility.

They also call on the prime minister to focus on ‘real problems’ facing schools, which they say are “continuing funding cuts, an unassuaged and escalating recruitment crisis”.

The letter is one of many recent examples of head teachers wielding their collective influence – aside from the lobbying of their unions.

Every state school head teacher in West Sussex put their signatures to a joint letter to the prime minister warning that they could have to cut school hours because of a lack of funding.

The House of Commons education select committee will be carrying out an “evidence check” on Tuesday on proposals to expand selection.

The committee’s chair, Neil Carmichael, said that since the plans for more grammars had been announced “the air has been thick with the sound of claims and counter-claims on the benefits and disadvantages of grammar schools”.

He said that it would be important for MPs to “get underneath the rhetoric and examine the evidence”.

The consultation on expanding selection will continue until next month.