London skyline: Duke of Cambridge Prince William and Prince Harry open the Leadenhall 'Cheesegrater'

The Duke of Cambridge Prince William and Prince Harry have unveiled a plaque at the Leadenhall Building – popularly known as the "Cheesegrater" – after the 46-floor skyscraper marked its official business opening. Building work on the £290m ($449m) tower, which at 224m is London's fourth tallest building, started in September 2011 and was completed last year.

Replacing the old office block at 122 Leadenhall Street, the Cheesegrater was designed by Rogers Stirk Harbour + Partners and is opposite Richard Rogers' famous Lloyd's building. It was developed by British Land and Oxford Properties and the building received the royal seal of approval when Princes William and Harry unveiled a commemorative plaque. The princes' appearance was despite their outspoken father Prince Charles' well-known view that London risks becoming overdeveloped.

Earlier this year a number of bolts on the skyscraper were replaced as a precautionary measure after a third fell off in recent months. In November 2014 two bolts on the fifth floor failed and dropped to ground level. A third bolt failed in January, but was retained by the installed ties. The bolts were determined to have failed by a process known as hydrogen embrittlement.