An office block often considered one of the ugliest in the city has found an unlikely defender in the form of one of the city's award-winning architects.

Built in the late 1960s, Sovereign House, once the home of Her Majesty's Stationery Office, looms over Anglia Square.

As part of the long-awaited revamp of Anglia Square, which will see it transformed into Calvert Square, the former office block is set for demolition.

But Anthony Hudson, director of Hudson Architects, which has offices in Redwell Street in Norwich and in London, said he would be sad to see the wrecking crews move in on a building he described as one of the best Modernist buildings in the city.

He said: 'Although much reviled by many, I admire the boldness which always catches my eye as I pass it on my way to work.

'It is one of the best Modernist buildings in Norwich and reflects an interesting period of English architecture, the so-called 'Brutalist' movement that spawned many buildings now regarded as masterpieces.'

Designed by Alan Cooke Associates, he said the building is a 'parochial cousin' to many of the best buildings of the great British architect James Stirling, and is worth saving.

He said: 'It's not just the pedigree or the fact that it's an interesting work of architecture which makes the imminent demolition upset me, but more importantly, nobody has thought properly about how it could be reused. 'In this age of profligate use of our natural and built resources we have a duty to make the most of our existing assets – if it were a pretty 19th century warehouse on the river nobody would think twice about converting it.

'The energy expended in creating this building was vast and to expend further energy to demolish it seems criminal without assessing its potential.'

He questioned why Sovereign House could not be turned into studios or workshops for young start-up companies and creative groups, such as happened at The Custard Factory in Birmingham.

That factory was saved from demolition and transformed into an arts and media quarter, complete with offices, studios, galleries, a theatre, bars and a nightclub.

In January, Centenary Ashcroft lodged revised plans for the multi-million pound regeneration of Anglia Square with Norwich City Council.

The plans include 178 new homes, a public square, new shops, restaurants, cafes and a healthcare centre, while Gildengate House, the office block over the entrance to the car park, will be updated to provide modern offices.

Ranald Phillips, a director at Centenary Ashcroft, said Sovereign House had become 'obsolete' and was not suitable for conversion.

He said: 'The facts speak for themselves. This was a building purpose built for the HMSO many years ago. Since they moved out several owners have found it impossible to find any interest in occupying it.

'It's been looked at in terms of residential use, but it just wouldn't work. It's a building which has become obsolete.'