The UK’s colourful new Berlin embassy offers Germans a glimpse of swinging Britain.

When the Queen opens her new embassy in Berlin next week, she will step into a kaleidoscope of colour. After passing through the front facade, which features a shiny mauve drum that would not be out of place in a Silk Cut advert, she will traverse a ceremonial route of grand halls, staircases and courtyards splashed with letter-box red, royal blue and lemon yellow.

The building is the result of a competition-winning design by Michael Wilford & Partners, whose Lowry arts centre completed three months ago in Salford is even more lurid. However, the embassy stops short of the angular forms that make the Lowry Britain’s tipsy answer to the Bilbao Guggenheim. In fact, it is more closely related to the Stuttgart art gallery of 1984, which bore the mark of Wilford’s former senior partner, the late Sir James Stirling.

The embassy exhibits a similar juxtaposition of formal classicism and free-form modern high jinks with which Stirling jazzed up the Stuttgart gallery. Its street facade is a strait-laced wall in limestone ashlar with regular rows of punched-through windows on the top two floors. This classical treatment was partly dictated by the city planners, as the building stands close to the Brandenburg Gate on the site of the old British embassy, blitzed in the war. But this demure masonry facade has been violently gashed through at first-floor level, allowing the mauve drum, a skewed section of modern curtain walling and a slanting picture window to spill out. It is as if the British ambassador appeared wearing his ceremonial dinner jacket over a psychedelic T-shirt.

The interior, in Wilford’s words, “is unashamedly modern, celebrating its freedom from constraint and representing Britain with dignity and splendour”. As well as the vivid colours, the interior features two courtyards, one open to the sky and centring on an English oak tree, the other an atrium beneath a glazed roof sitting on a diagonal lattice of steel beams. The atrium roof and upper storeys are supported on plain, slender cylindrical columns that intersect the larger ceremonial spaces on the ground floor.

The ambassador’s suite occupies the two top floors. “It overlooks both the street and entrance courtyard – symbolically at the interface between Britain and Germany – and forms the culmination of the ceremonial route,” says Wilford.

The embassy was developed as a private finance initiative in which a German-American consortium was contracted to build and run the building for 30 years. The present net cost of the PFI is £49.8m, which, according to the National Audit Office, achieved a marginal saving of £1m over a traditionally procured building – but at the cost, says Wilford, of adding a year to the development process.

Despite the tribulations and delays, Britain has ended up with a striking embassy that fits the vibrant spirit of born-again Berlin.