New wonders among old shelves at the London Library

The Royal Court Theatre, the Young Vic Theatre and the London Library (above) are buildings of varied character and rich history. What they have in common is that each has been unpicked and reassembled by the architects Haworth Tompkins, recently announced as winners of the RIBA London Architect of the Year. This firm, founded in 1991, often gets chosen to make practical improvements to existing institutions and manages to make them work with a panache that allows the original building to retain its character. In an architectural world where severe contrast between old and new confronts the alternative of invisible and seamless extension, they have always managed to get somewhere in between.

An element of play-acting often comes into their work, not inappropriately for specialists in theatre refurbishment. The Royal Court, completed in 2000, was a striking example of their tough love towards buildings of character but not of high architecture, scraping the surfaces down as if the theatre had been rescued from ruination.

The London Library remains what it always was — a hallucinatory maze of open shelving and surprising staircases, reached through a club-like frontage. But as Haworth Tompkins’s ten-year programme of work there nears completion, the expansion of space and joining up of the maze has been achieved without disturbing the atmosphere, new meeting old on cordial terms. It tells in the small details, like the switching between timber and metal handrails or the unexpected outbreak of colourful marble floor tiles in the basement lavatories.