Unison Building, Euston Road

Although they don't, funnily enough, tend to be considered part of the Big Society, Trade Unions are still, by an overwhelming margin, the largest civil society organisations in the UK. The Unions are voluntary, democratic, mutual, bottom-up, and yet they're the very obverse of 'localism', philanthropy and the other current shibboleths. Membership might have declined since its late 1970s peak, and a series of amalgamations might have swallowed up many of the once-influential unions, with even the fearsome Transport & General Workers Union absorbed into the most recent of them, Unite – but Union membership still stands at seven million, which puts the much-vaunted likes of, say, London Citizens in the shade. And paradoxically, the frontal attacks on public sector unions from the coalition has revealed their unexpected strength, whether in the half a million who marched in London on March 26 or the 750,000 or so strikers who walked out last week. The largest, along with Unite, of today's amalgamated super-unions, the public sector union Unison have just begun occupying the first purpose-built trade union headquarters to have been erected in the UK for nearly thirty years. While as a piece of architecture it's quite deliberately unspectacular, Squire and Partners' building shows a face of the trade union movement that is seldom seen. The stereotypes of donkey jackets, gavel-bashing and intense masculinity are wholly absent – instead, this is quite consciously an exercise in branding and modernisation. It suggests what the 1997-2008 era's Blairite buildings might have been like if Labour had remained a socialist party. It's a fascinating, occasionally rather inspiring place. But the first thing to note about the Unison building is what it is not.

Oddly, given their once-central and still key role in British political life, trade unions have not always been major sponsors of architecture. The most famous of them is in central London, in the form of David Aberdeen's Congress House for the TUC, a very expensively detailed Corbusian palazzo, with its Jacob Epstein sculpture and craftsmanlike finishes. It is one of several in the Bloomsbury/Kings Cross area, near to the termini serving the North and the Midlands, traditionally the unions' strongholds. Even now, the NUJ, Unite and others are nearby. Also in the area is the original headquarters of the National Union of Mineworkers, a stripped classical building now occupied by University College. The NUM moved out of here even before their fateful defeat in the Miners Strike of 1984-5, to a purpose-built headquarters designed by Malcolm Lister – relocated to Sheffield, as a gesture of distrust to Union leadership's tendency to get cosy with the Great Wen. It was left unfinished at the end of the strike. Unison's tower is almost certainly the first of its kind since then. It even has the odd stylistic similarity, with both centring on severe columns as a slightly strained metaphor for mutual support. It's worth remembering that Dave Prentis, the head of Unison – not a leader who is exactly known as a firebrand – has said of the current wave of public sector strikes that it will be unlike the Miners strike, as 'this time, we'll win'.

The air of siege and conspiracy that all this might imply is conspicuous by its absence; no union barons or smoke-filled rooms to be seen. Michael Poots, the project architect at Squire and Partners, talks of it as a 'corporate headquarters'; Unison's site manager John Cole speaks of a 'bold high street frontage', and both talk about it as a form of branding, a statement of what trade unions are in the 21^st century. Cole contrasts it with the office block Unison previously occupied just across the road – a large, slit-windowed, Gorilla House concrete tower which he refers to as 'the East European grey concrete building'. The union had considered moving to the City of London (before deciding that 'culturally, it didn't quite fit'), but decided to stay near to other unions and to the termini for the North. But happenstance has meant that the new Unison building directly faces the old.

Originally designed for the local government union NALGO, one of those that merged into Unison, Cole says of it now that 'it was basically a concrete tower block', although this is also a fair description of the most obvious element in the new Unison building. To the Euston Road, it is a concrete-clad, steel-framed tower, with a mild case of the barcode façades and a rhythm of different window heights; but this becomes more complex at the rear and the side, where that corporate symbol, a glass atrium, links it to the listed Arts & Crafts Elizabeth Garrett Anderson building, a former women's hospital, and at the back, a small cluster of housing. It's a complex more than a singular building, although this is hardly apparent from the laconic street frontage, where the most notable moment is the aforementioned branding. A large UNISON logo at the top and at the entrance, making the purpose-built nature of the project apparent, and announcing the union's public presence.

The main bulk of the complex is the office block in the tower, spilling into the Elizabeth Garrett Anderson building, and curiously it's here that the difference between this place and any other corporate headquarters is most apparent. On one level, it's a question of rhetoric. You find the brightly coloured sloganeering that adorned some Blairite structures, but the content is very different. Instead of, say, AHMM's Westminster Academy and its Mandelsonian mantra of 'Enterprise, Global Citizenship, Communication', each room features the rather more meaty, contentious 'Solidarity, Participation, Democracy, Equality'. What would once have been called 'improving quotations' are also littered around the building, inscribed into glass doors and internal windows, with 'everything from Mahatma Gandhi to Billy Bragg'. Most memorably, given that the UK has, as Tony Blair once proudly pointed out, the most repressive labour laws in the western world, one wall comes via Michael Foot: 'most liberties have been won by those who broke the law'. All this heated (albeit soft-toned and lower-case in the graphic design) rhetoric has to have some sort of correspondence to how the building actually functions. Given that the organisation exists at least in part to fight for better working conditions, it had to be 'an exemplar working environment' And here Unison are clearest about the old NALGO building's limitations. Dark and lit by artificial light, John Cole also points out that it had 'no social spaces'. Instead, the union 'wanted large floor plates' in order to be able to create these areas. In the concrete tower block, there's a very pleasant roof garden, a cafe, a creche, a 'breakout room' and much else. In design terms, these aims are compromised a little by the rather cold, identikit corporate detailing. Cole comments that opulence was out of the question, as 'we have lots of low-paid members' (something that certainly didn't deter the designers of Congress House in the 1940s) but there's no doubt that they work. When walking around it I chance upon a small office get-together, with crisps and what is (euphemistically?) described as 'juice'. One comments that in three days there, she'd met six fellow Unison employees she'd never met before. 'It shows how a building can change things'.

Most of the workers I saw here were women, and the building seems to – perhaps inadvertently – reflect where Unions are currently strongest, in poorly-paid but traditionally 'white-collar' jobs, largely female, and highly computer-literate. In the face of accusations that unions are lumbering pre-modern dinosaurs, Cole proudly points out that Unison has the the largest intranet in Europe, and Michael Poot lists with equal pride the building's impeccable environmental credentials. Given the evident successes of the internal arrangement, the lightness and airiness of the place, it's a shame that its design language stays at such a low voltage.

That's something which becomes especially clear with the transition to the Elizabeth Garrett Anderson building. This late 19^th century hospital was closed in 2002, with its functions transferred to nearby UCH. The complex entailed a complete restoration of its much smaller, cosier rooms, with the original tiles and fireplaces scrupulously pieced back together. Sometimes this leads to enjoyably surreal juxtapositions, as when a vaguely art nouveau fireplace sits unused in the corner of a video conference room. Irrespective of the TUC's brief foray into high modernism, the most famous visual image of trade unionism is deeply Arts and Crafts-influenced – the embroidered trade union banners that are still carried on marches, where the aesthetics of William Morris socialism, in a pre-branding era, still have a vivid emotional role. Framed with foliage, symmetrically organised and allegorical, sometimes you even find architectural modernism immortalised on them. One RMT banner I spotted on a protest a few months ago was centred on an image of Charles Holden's Arnos Grove station. This powerful language is at least partly present in the Elizabeth Garrett Anderson building. In its main room, which is being adapted as a museum, with interactive exhibits on feminism, the health service and trade unionism, there is remade arts and crafts furniture (that you can sit on, for once!) and a small library, featuring the likes of Friedrich Engels, Mary Wollstonecraft, Sheila Rowbotham. If the rest of the building avoids the traditional notions of what trade unionism looks like, here there's a reminder, and its a quietly powerful one. Perhaps this is a project which needed rhetoric and imagery as much as clarity and spaciousness. While Squire and Partners clearly took the place very seriously, a more nonconformist firm might have reconciled the traditional and forward-looking impulses of the union in a more forthright, convincing, dialectical way. Instead, the pretty but mute faceted roof of the atrium provides the main connection.

The atrium also leads the way towards the housing that was demanded by planning – deceptively so, as there is no public access. It's a decent, unspectacular, stock brick scheme of houses and flats, 'mixed' as ever, and clearly demarcated between the private element facing one way and the 'social' side the other, with both quite aggressively gated from the street. Here, you're reminded that the context is the redevelopment of Somers Town and Kings Cross, a working class industrial area of dense council housing undergoing severe gentrification, from HOK's BioMed Centre behind the British Library, that was fiercely opposed by local campaigners who pointed out that the site was zoned as social housing, to the new St Pancras International and King's Place. It's the sort of area where unions used to thrive, being completely transformed. The Unison building shows trade unionism transforming in turn, and in that, it's an optimistic, encouraging building, an enclave of sobriety and solidarity in amidst the regen tat. It stands its ground, quietly – but in terms of what happens inside, this might well prove to be one of the more influential recent buildings in London.

Originally published in Building Design, 6/7/11