A run-down secondary school is to finally be rebuilt after years of delays.

Plans for Archbishop Lanfranc's multi-million-pound new building were unveiled this week, with the school's headteacher confident it would help to "win back" pupils put off by its present poor state.

The four-storey building will also allow the Mitcham Road school, which last year became an academy as part of the Coloma Trust, to expand to become one of Croydon's biggest.

Its capacity will rise from 1,050 pupils to 1,350, divided into nine classes in each year instead of seven, with a new sixth form accepting up to 270 further students.

Work is due to begin on the 11,796sq m building in August, with pupils scheduled in move in the start of the 2016 academic year.

The school's current home, constructed above a landfill site in the 1950s, has long been deemed outdated and dilapidated. But plans for a new building have been repeatedly delayed over the last few years.

Headteacher Michael del Río said: "The state of the building here has been a concern for years really. In the long-term the school has now got a much better future.

"It has always been very much a community school and we believe that at the moment some of the students that live on our doorstep may choose to go to schools that are further away or out of borough, simply because they are wowed by new buildings and new facilities - as you are when you are 11 years old.

"One of the key things for us therefore is to win back some of those very local children who at the moment go off to other schools."

State-of-the-art classrooms, a full-length athletics track and bigger sports hall are among the facilities planned for the new site, on the south-east corner of the current school's playing field.

The old building will be demolished when the new one is built to allow the school to remain open.

Construction firm Galliford Try, which won a £45m Education Funding Agency contract to build the school and five others, will also carry out remedial work on the landfill site to flatten Archbishop Lanfranc's infamous lumpy playing fields.

The school was allocated funding for a rebuild under Labour's Building Schools for the Future Programme until that was scrapped by the coalition government in 2010.

It was again prioritised for building work by education secretary Michael Gove in 2012.

At the time, then headteacher David Clark described the school's building as unfit for purpose. He said: "The design of the building is not fit for a school in the 21st century.

"It has very narrow corridors, and staircases, some of the rooms are too small and there is no room to expand.”

Mr del Rio, who moved from a deputy headteacher post at the Quest Academy in the summer, said: "I know staff have been through this process twice before and been disappointed, but they are very much behind the project this time around and certainly from our perspective things look very, very bright and we are now in the final stages of planning approval."

Pre-application plans for the new school will be reviewed by Croydon Council's planning committee tonight.