Architecture: A high-rise faces a hard fall: An East End tower block is a victim of prejudice, argues Rowan Moore

THE CASE for the demolition seems overwhelming. Pieces of concrete are falling from the sky, the building is skirted with nets and hoardings, and almost all the residents were hurriedly evacuated last year.

A few valiant souls remain behind their fanlighted, mock-Georgian doors. The other flats have had their orifices stopped with breeze blocks, and vagrants light fires on the escape stairs. Most damningly of all, Keeling House, in Claredale Street, Bethnal Green, east London, is a tower block.

The tower block has become the symbol of everything that was wrong with paternalist, diagrammatic, doctrinaire post-war planning. In spite of recent outbreaks of revisionism - some city towers have been revamped and some, such as Trellick Tower near Portobello Market in west London, have even become fashionable - it remains an object of scorn.

The Bethnal Green neighbourhood division of Tower Hamlets council, which is responsible for the block, wants Keeling House to be pulled down and replaced. But this is no ordinary tower block.

Completed in the late Fifties, it is the work of Sir Denys Lasdun, also the architect of the National Theatre and the Royal College of Physicians in London and the European Investment Bank in Luxembourg. This fact does not on its own guarantee the worth of Keeling House, but the building is significant in its own right - because it was designed as a reaction to the paternalist and diagrammatic planning with which it has now become associated. This was the tall housing block that was to emulate old patterns and virtues of London street life. It initiated the very movement away from dogmatic modernism that its detractors believe it to represent.

Instead of being composed of monolithic facades, endless corridors and tyrannous right- angles, the block is broken down into interconnected towers, paired maisonettes and flats. As in a street, the identities of the individual parts are expressed within an orderly whole. As in a street, the approaches to the flats - in this case a system of balconies - offer the chance to talk to neighbours. Unlike a traditional street, the height and angle of the towers admit abundant sunlight and create wonderful views over London.

This does not mean that the block should automatically be preserved. The above might be only a list of good intentions, imperfectly realised. Vices might offset virtues, most obviously the replacement of gardens in traditional housing with balconies (although in Bethnal Green 'gardens' are rarely more than dingy yards). The place might be a nightmare to live in. But the fact that it has been designed with care by a man of talent does mean that it should not be wantonly destroyed.

Its physical condition is largely the result of neglect, not of the original design, compounded by botched 'repairs'. Council officials appear unable to produce conclusive arguments for demolition. They will quote the estimated cost of repairs - pounds 3m - but not the cost of demolition and replacement, which is bound to be higher. Any replacement scheme would fit in considerably fewer homes than the site now contains. It is unlikely that new flats would be as generously proportioned as the old ones, or that a new scheme would offer much more play space for children.

Evidence of social shortcomings is equally elusive. When the residents were moved out, many objected vociferously. According to one councillor, a significant number of older tenants were reluctant to move out, while younger residents were keener to go; and the desire to move may have owed as much to the danger from falling masonry as to dislike of the architecture - a reversal of the early days of tower blocks, when architects confused tenants' appreciation of baths and inside lavatories with a fondness for their work.

If the tower block were demolished, the cost of a replacement would not be the council's concern. Most public housing is now built not by councils but by housing associations, funded directly by the Government through the Housing Corporation, and the money that councils can spend on their existing stock is limited. In Bethnal Green, Tower Hamlets council has found a housing association which, working with a private developer, is offering to redevelop Keeling House in conjunction with two other sites.

The council is presented with an unequal choice between new housing at no cost to itself, and an expensive renovation. No single body will simultaneously judge the issues of cost, use of land, social usefulness and architectural merit.

There is, of course, a legal mechanism designed to prevent arbitrary demolition: the listing of buildings. By all the criteria of the process, Keeling House - which is being considered for listing - should be protected. A major work by an important architect, a turning point in the development of housing, it is much more remarkable than many of the Victorian developers' speculations that are dignified with listing.

Although some modern buildings are now protected, including two by Lasdun, none of these is council housing. Although officially the Department of National Heritage considers each case on its merits, what are now seen as monuments to socialist housing policy seem unlikely to be listed. If the aesthetic values of the modern movement are now being recognised, its social aims are not. In national as in local government the tower block remains, by definition, a Bad Thing.

What is disturbing about this attitude is that we have been here before. It is the mirror image of the post-war revulsion against slums. Nowhere was that sense of outrage more justified than in Bethnal Green. In 1945, 89 per cent of the area's houses had no bathrooms, and even today, in spite of the sentimentality lavished on the remaining Victorian houses, its streets appear mean, pinched and arid. After the war the reaction was to try to sweep everything away, regardless of individual cases, people's attachment to their homes, and the possibility of less drastic alternatives.

Now, in reaction to the equivalent ill of tower blocks, there is the same apocalyptic thinking, the same blindness to the particular. Judgements are based on emotion and prejudice. Keeling House should be given a fair trial.

(Photograph omitted)