For 25 years, around 15 works by the elusive British street artist Banksy have adorned the walls of the underground car park at the Swiss embassy in London. The collection, kept largely out of public view, is believed to be the most concentrated group of Banksy murals in a single location. At the official residence of the Swiss ambassador to the Court of St James’s, Switzerland presents itself in refined fashion. Chandeliers, monumental tapestries by Le Corbusier and works by Max Bill welcome parliamentarians and visiting delegations hosted by Ambassador Dominique Paravicini. Beneath the residence lies a very different setting. The embassy garage is covered in brightly coloured street art. Around 50 works decorate its walls and pillars – 16 of them attributed to Banksy. When Paravicini took up his post, he was struck by the contrast. “I was surprised by all the colours in this garage,” he told Swiss public broadcaster RTS. “It’s an incredible asset for our work as ambassadors. It’s ...