You just can’t get rid of some architects. If they are successful, everyone wants to use them. The older they get, the more in demand they are. It was true of America’s Frank Lloyd Wright and France’s Le Corbusier; it’s true today of America’s Frank Gehry, Italy’s Renzo Piano and Britain’s Richard Rogers and Norman Foster. This has always been an art in which wide acceptance comes relatively late in life – though these are striplings compared with Oscar Niemeyer, creator of Brasilia and still working at 100. Even so, we’re now at a pause moment. What comes next?

The problem is most acute here in Britain because we have enjoyed a long, golden era of architectural eminence. It might not have seemed quite that way to those of us living here, but that is because we generally mistrust our best architects and force them to make a name for themselves overseas. That’s what began our last great period. When Rogers and Piano, with no work to speak of in Britain or Italy, jointly won the competition to build the Pompidou Centre in Paris in 1971, the nascent style known as high-tech hit the world stage. Rogers’s former partner, Foster, was close behind: his Willis Faber (now Willis Corroon) building of 1975 in Ipswich is now Grade I-listed.

That tells you everything. When a given style is regarded by con-servationists as historically important, then plainly it is no longer current. High-tech is still a saleable currency - look at Foster’s mega-projects in Russia and China, or Rogers’s billion-euro Barajas airport, in Madrid, so much better than his compromised T5 at Heathrow. Rogers is also enjoying a retrospective at London’s Design Museum, fresh from its showing at the Pompidou. Younger architects don’t design like that, however. It’s so last century. Incredible, in a way, it has had the run it has.

Nor do the younger architects default to one of the other tropes of recent times – the “polite modern” white box. Recently derided by Kevin McCloud, of Grand Designs fame, the white box is a 1990s thing, in truth, and has - like the weird-shaped-icon-building boom - run its course.

Rogers’s cooperatively run firm is now known as Rogers Stirk Harbour. Ivan Harbour, one of those younger names, is responsible for England’s first Maggie’s cancer-support centre, just opened in Hammersmith, west London. It’s a graceful, cheerful, modest and necessary little building, and it is nothing like the work his boss used to do. Handcrafted, solid-walled, richly coloured, not remotely mechanistic beyond the gesture of its floating roof canopy: arguably, this is not so much in the high-tech tradition as in the Arts and Crafts tradition. Which, appropriately, defined the last high point of British architecture, a century ago.

Harbour’s Maggie’s Centre, however, does not engage with the latest obsession in British architecture, known as new ornamentalism. In a nutshell, ornament is no longer a crime. Actually, a lot of high-tech was ornamentation by stealth - all those exposed struts and pipes were ways to dress up a basic box - but there was always an underlying functional rationale. With new ornamentalism, there is no such thing. Ornament is ornament.

It has been around for a while - Will Alsop, always the maverick, never had any crisis of conscience over strictly unnecessary decoration. From his Stirling prize-winning Peckham Library to the black-and-white box on stilts that is his Sharp Centre for Design, in Toronto, he blazed a trail in the jazzy-surface treatment of low-budget buildings.

Alsop champions one of the larkier younger sets of architects, the firm known as Fat (it stands for Fashion, Architecture, Taste, provocative words when it set up shop in the late 1990s). Fat is now getting to build, rather than merely goad people, as it did in the early days with manifesto slogans such as “Kill the modernist within”. Take the abstracted (concrete) gothic screen of the Sint Lucas art academy, in the Dutch town of Boxtel. It is actually a very old architectural device - the imposing new facade uniting a less than sublime collection of older buildings behind, in this case from the 1960s. It is none the worse for being lightly leavened with humour.

The same is true of the new John Lewis store in Leicester, now being completed by one of the starrier younger names of the moment, Foreign Office Architects (FOA). Department stores, like theatres and art galleries, are blank-walled boxes that have to be dealt with somehow. FOA are a deadly serious bunch, but in Leicester they used net curtains - sold by the kilometre in John Lewis - as an inspiration. The result is a hugely enlarged filigree pattern, sandwiched in glass to form the building’s skin. When were net curtains ever trendy? In this form, they are.

The equally serious firm of Caruso St John, best known for its austerely beautiful New Art Gallery, in Walsall, shocked its fans when it fervently embraced multicoloured patterning on its Museum of Childhood extension in Bethnal Green, east London, in 2006. It is now building an arts centre in Nottingham with coloured concrete panels, moulded, again, with local lace patterns.

New ornamentalism, however, comes in many forms. Some architects still can’t stomach pattern-making for its own sake. Instead, they shuffle the windows around, use bright colours, work with artists or do all three simultaneously, as another younger firm - Haworth Tompkins - has with the Coin Street Neighbourhood Centre in Waterloo, central London. There, it worked with the artist Antoni Malinowski, a partnership dating back to their Royal Court Theatre rebuild. It is as if artists have licence to do things architects cannot. They give permission to be unfunctionalist.

What does all this tell us? That, following the eclipse of high-tech, the pendulum swing between rigorous, minimalist modern and decorative postmodern has slowed to a halt. There are no longer knee-jerk value judgments to be made about what is good and bad, style-wise. We are at an interesting moment. Yet, although new ornamentalism is the most obvious of various trends going on - shaggy eco-tech is another, the sort where buildings sprout plants and wind turbines - these don’t add up to a movement as internationally significant or long-lasting as high-tech.

I look at it this way. If Arts and Crafts faded at the start of the 20th century, and high-tech at the start of the 21st, then how long to wait for the next authentically British architectural movement? Quite some time, probably. All that pattern-making might just be architects doodling while they try to think up something new.

Richard Rogers, Design Museum, SE1, until August 25; www.designmuseum.org

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