The new institution, which will come into being after Easter, will have all the cosiness of a school combined with a range of courses to match a sixth-form college, its supporters claim.
Laurie South, a governor of Southborough, one of the three schools involved, said they were all successful and expanding institutions but lacked the resources to meet the requirements of Curriculum 2000.
He said: "It seemed more sensible to join forces at the top and give the sixth form a new name."
Southborough, Chessington Community College and Hollyfield, all with sixth forms of less than 50 pupils, decided to merge and gave the new institution the name Kings Sixth Form College.
The new consortium has caused a furore, both in the local authority and with other heads.
The decision was made without reference to the authority which was seeking a collaborative solution to sixth-form provision in the borough.
Clarissa Williams, head of nearby Tolworth girls' school, which has a mixed sixth form of 200, said the name was "ridiculous" and "in danger of seriously mileading the public" who might confuse it with Kings College School in nearby Wimbledon on one side and Kingston College of FE on the other.
So the three heads, now dubbed the "three kings" by their colleagues, changed the name to Kings Sixth Form Collegiate to differentiate it from the others in the area and give a distinctive ethos.
The name change has enabled the consortium to avoid the lengthy procedure of joining the Further Education Funding Council as a sixth-form college.
Under the terms of the Learning and Skills Bill, now at committee stage in the House of Commons, it will be guaranteed funding for three years if numbers do not fall.
The future of school sixth-forms, already a hot political issue nationally, looks likely to surface in next year's local government elections.
Local Conservatives, who are likely to seize control of the LEA, are now taking their lead from the party's national spokesperson Theresa May.
Last week, she threatened to fight the Learning and Skills Bill tooth-and-nail as a "levelling-down agenda", aimed at abolishing school sixth-forms in favour of FE colleges.
She said: "Heads and governors should be free to retain, set up or expand their own type of sixth-form education."