In a way, architect John Melvin explains, everything really grew out of a cockleshell. For a moment it is difficult to know whether he is talking about the Greek goddess of love, Wadham College or his new book on what is good and bad about Oxford’s development down the centuries.

There’s no doubting the fact that Aphrodite certainly emerged from the foaming waves, carried on a scallop shell all the way to Cythera. A scallop shell also happened to be the heraldic symbol of Dorothy Wadham, who contributed a sizeable part of her fortune to build Wadham, the first college created in Oxford since the Middle Ages.

But it is indeed Mr Melvin’s new book, subtitled The Stones of Oxford: Conjectures on a Cockleshell, to which the architect is referring.

For the idea of the book came as he took Alexandra Papadakis, owner of the architectural book company Papadakis, around the Holywell Music Room to inspect the improvements to the 18th-century concert hall, that Mr Melvin helped orchestrate.

The music room is owned by Wadham and Mr Melvin explained how the cockleshell was prominent in the college’s arms. The shell, the symbol of St James, has connotations of pilgrimage and the crusades going back at least 3,000 years.

“I told her how the sculptor John Blackshaw had used the shell to provide a canopy over the college’s two founders, Dorothy and Nicholas Wadham in the frontispiece. She was fascinated with the story of the college and the cockleshell.”

She was equally intrigued by the story of Dorothy’s father, William Petre, who ended up becoming a principal secretary of Henry VIII and accumulated great wealth from the sequestration of the monasteries.

The publishing director suggested that it would all make a good subject for a book.

But as a man with 50 years’ experience working as an architect and town planner, Mr Melvin, who lives in Chipping Norton, was not going to miss the chance of setting out his own views about the buildings of Oxford and the town planning disasters that have scarred the place he regards as his adopted city for 35 years.

He has come to regard himself as “an entranced outsider” on the basis that, in his view, being an insider means taking the place for granted or becoming “one of those impossible grandees who can only exist in the rarefied atmosphere of academia”.

Mr Melvin reached this conclusion on seeing one of Oxford’s great philosophers stalking the foothills of Belsize Park in London.

“Isaiah Berlin wore what appeared to be a gas mask around his neck; possibly no one had told him that the war had ended 40 years before — or was it a precaution against contamination from alien atmosphere? Anyway, he seemed as furtive and incongruous away from All Souls as the Pope would if caught stealing out of the Vatican to buy a packet of Woodbines.”

But even his affection for the city has been put to the test in recent years with “infantile and banal architecture” that makes even Slough look a more attractive proposition for shoppers.

“Unless planners engage and recognise that they must upgrade the commercial centre, people will vote with their feet and not come to Oxford. Not long ago a BBC poll voted Cornmarket the second worst shopping street in the country,” he said.

“If we compare the street today with the Cornmarket of 100 years ago, we can see the source of the aesthetic failure. The engagingly detailed shop front has been superseded by the ubiquitous plate glass.

“The tragedy of the post-war generation is that three large developments have undermined the original scale and rhythm of the street. They only convey a sense of dumb anomie.”

The fact that the city council and colleges own much of the land in the city centre means that they must share much of the blame, he insists.

He said: “What colleges have done for college buildings is admirable. But they must exercise the same care for other buildings in the city. They must not simply take the short-term view and leave it to surveyors.

“It is in the colleges’ own long-term interest to make Oxford’s commercial centre as attractive as possible. In Cambridge they have exercised much more care with their commercial buildings — there is not this discontinuity between town and gown in terms of architectural experience.”

The Clarendon Centre provokes most contempt.

“We enter a sanitised and infantilised world, divorced from any sensory stimulation or imaginative engagements except that provided by the anodyne chain store,” he writes.

“Planners need to know what they are after, what they are aiming at. If they have not got the necessary skill they should go out and buy it,” said Mr Melvin. The alternative is to allow “outrageous out-of-scale designs” such as the Westgate car park.

“Buildings can extinguish the life out of a city. This is dangerous. Of course, all cities change, but if that change brings in its wake a coarsening and loss of aesthetic awareness, then the loss is likely to spill over into the lives of its citizens.”

But despite all the damage inflicted and missed opportunities, the future need not necessarily be bleak, argues Mr Melvin. There are buildings of outstanding architectural merit at both ends of Cornmarket, the Golden Cross represents “an intriguing enclave” and there will be an opportunity for redevelopment as leases come to an end.

Mr Melvin can surely count himself as an architect who practises what he preaches. He became involved in the restoration of the 260-year-old Holywell Music Room, where both Handel and Haydn appeared, after being approached by Caroline Miles, a music-loving economist and former chairman of the then Oxfordshire Health Authority.

As an opera lover with wide experience working on listed buildings it proved an irresistible challenge, with many viewing the concert hall in Holywell Street as the most important chamber music concert hall outside London.

The novelist Justin Cartwright, author of This Secret Garden: Oxford Revisited, reckons the redevelopment of the music room “demonstrates that it is perfectly possible to meet the needs of the 21st century without trampling on the history of human endeavour that has gone on before”.

When Mr Melvin was working on the Holywell Music Room he became aware of the divergence of opinion in Oxford on something as simple as railings.

For Mr Melvin the suburban houses of North Oxford have still to recover from the loss they suffered by the removal of their railings during the Second World War. Part of the blame seems to go back to George Orwell, who had deplored the restoration of railings in Bloomsbury’s Bedford Square.

“Orwell maintained that these railings had, by excluding the public, amounted to theft by the rich from the heritage of the ordinary man. Orwell seemed oblivious to the aesthetic consequences of omitting railings and to the role that these railings played in the overall design of the square.”

But if The Stones of Oxford has one message, it is that the city can never be the subject of a single vision, but rather needs to reflect multiple interests, neither succumbing to a rigor mortis of the post nor “to some nostalgia for an imagined utopian future”.

It is amazing where a little conjecturing on a cockleshell can lead.

  • The Stones of Oxford: Conjectures on a Cockleshell by John Melvin is published by Papadakis (£25).