Children from aged 11 are being segregated, taught in colour-coordinated buildings, playing in separate fenced-off areas and eat lunch at different times.
The move has caused concern that it is stigmatising children who are placed in lower quality sets.
Pupils are ranked as they leave primary school and placed into one of three mini schools at Crown Woods College, Greenwich.
The brightest go to Delamere and wear purple ties and purple badges. The rest go to Ashwood, which wears blue, or Sherwood, which wears red.
The two latter schools are made up of pupils with mixed abilities but are still streamed into three tiers.
Critics have warned that the move is demoralising for pupils and encourages resentment and animosity amongst those in different sets.
Michael Murphy, the head teacher at the comprehensive, said: “I felt if we made explicit the provision for high-ability children we would be able to attract those children and their parents who would rather not put them in to a grammar.”
“Mrs Thatcher said you can’t ignore the market, you have to respond to it.”
Kevin Courtney, deputy secretary of the National Union of Teachers has condemned the practice.
He said: ‘The idea of taking a large school and turning it into three mini schools is likely to be good for [the school’s] relationships, but streaming is a step backwards. It leads to competition for children rather than improvement in teaching.”