Work is under way on transforming Merton’s tallest building, the Brown & Root Tower, into luxury flats.

The vacant building is being extended to create 150 new flats and a parade of shops during phase one of the project.

Planning permission has been granted to build a further 68 apartments to the south of the site.

Owner Criterion Capital has appointed contracts to Weston construction group, to begin work on the interior of the building, while the black tower is also being encased in glass to make it more attractive after interior work has been completed.

Scaffolding has been placed around the 17-storey building, with minor road works expected to affect the surrounding area.

It follows campaigning from Merton Council and MP for Mitcham and Morden Siobhain McDonagh.

Leader of the council, Councillor Stephen Alambritis, said: “It is really good news for the area. The council has pushed and pushed and worked with Siobhain.

“It has been a land bank for a number of years. It was voted the ugliest building in London.

“It is good news for the residents of Colliers Wood.”

Planning permission to develop the site was granted in 2003, but stalled on numerous occasions before Criterion Capital became involved in the scheme two years ago.

Construction is hoped to be completed by August 2015, and is part of a large scale regeneration of Colliers Wood.