The public inquiry into plans for three tall buildings next to Waterloo Station at Elizabeth House in York Road has heard closing submissions from developers P&O, Lambeth Council, Westminster City Council and English Heritage.
P&O got the go-ahead for two office towers and a residential tower of 274 homes last summer but a public inquiry was ordered by communities secretary Hazel Blears.
Westminster City Council and English Heritage have sought to demonstrate that the towers would have an unacceptable impact on Parliament Square as well as views across the river to the Royal Festival Hall and National Theatre.
"There is no evidence before the inquiry that suggests that the benefits of the proposals can only be – or even can most advantageously be – provided by a scheme in this or similar form," said Peter Harrison QC for Westminster City Council.
He reminded the inspector that the buildings proposed are in the region of the height of Centre Point, and as tall as the Shell Centre or Millbank Tower.
"None of the buildings is of the conventional tower proportions, with the height to width ratio giving a slender appearance that has often been a key element of the architectural quality of the buildings as well as playing a key part in any judgement of the degree of impact on any views in previous tall and super-tall building cases."
Turning to the scheme's impact on the Palace of Westminster World Heritage site, he said that Big Ben is "one of the pre-eminent symbols of Britain – a visual and aural shorthand for the whole country".
Mr Harrison warned that the the appearance of the Waterloo towers in views from Parliament Square would "reduce the appreciation of the asymmetry of Westminster Palace".
"If permitted, the harm to the heritage assets would be permanent and in truth irreversible.
"The consequences of refusal, whilst hugely frustrating to the applicants, would not be so stark."
He concluded: "A decision to refuse planning permission would not be any doctrinaire statement against tall buildings. It would neither advance nor derail any other tall building proposal. It would simply be a sustainable planning decision that these proposals, with their form and bulk, would cause more harm than benefit ..."
"The application proposals represent overdevelopment which would cause unjustified harm to heritage assets."
Neil King QC began his closing submission by stating that "English Heritage believes that the development of Elizabeth House proposed in this current application would cause substantial harm to the setting of listed buildings and conservation areas of local, London-wide, national and international significance".
"It is under a duty in those circumstances to advise the secretary of state accordingly."
"The fact that the secretary of state has called in ten applications for tall buildings in central London in recent years and has granted planning permission for all seven of those that have been determined in no way affects that duty."
Mr King said: "English Heritage's greatest concern about the Elizabeth House proposals is the effect they would have on the setting of the Palace of Westminster and the clock tower in particular. Their greatest impact, however, would be on the setting of the Royal Festival Hall.
On the Houses of Parliament, he said: "There is perhaps no other building in the UK the setting of which it is more necessary to cherish and to protect."
He complained that heritage considerations appeared to have played no real part in the design of the scheme and queried the quality of the design by Allies and Morrison: "I am questioning whether the architecture is so great. No other architects have supported these proposals."
He raised the prospect that English Heritage might be able to support a more slender, taller building at the northern end of the Elizabeth House site as this would not have such an impact on views from Westminster.
Mr King concluded: "English Heritage ... believes that in the present case the harm that would be caused to the setting of some of London's most important historic buildings is so great that its standing as one of the world's great cities would be noticibly and irrevocibly diminished."
"The fact is the impacts on heritage assets of the scale, bulk and massing of the proposed buildings are such that in the English Heritage view they could not be substantially be mitigated.
"No amount of deep incising or gilt colour plate could remedy the fact that as English Heritage sees it these buildings are too big."
"The public realm and permeability of this site would be transformed out of all recognition for the better and the common good," he said, highlighting the "exceptional" improvement offered over the current "dire" York Road streetscape.
Mr Katkowski explained how the Mayor's Waterloo Opportunity Planning Framework identifies the Elizabeth House site for "highly visible" tall buildings.
He complained of the "crude and misleading" images of the proposed development produced by Westminster City Council which he said failed to show the buildings in their wider context.
He also complained that English Heritage had failed to consider the architectural merits of the scheme when assessing its impact.
"One cannot decide whether a proposal would cause harm, and if so, to what extent, simply by considering its height and silhouette; the entirety of all those elements that would go to make the new building a fine or a poor work of architecture surely need to be brought into the equation."
Turning to the question of the Palace of Westminster, Mr Katkowski sounded a note of caution about English Heritage's ability to "overstate impacts on the World Heritage Site".
He pointed out that other consented tall buildings – including the Shard at London Bridge, the Doon Street tower and 20 Blackfriars Road – would appear in the gap between the Palace of Westminster and Portcullis House when viewed from Parliament Square.
"But Big Ben is such a powerful tower in its own right that the buildings and structures that lie on the other side of the river, on the South Bank, cannot and do not undermine one's ability to appreciate it."
He added: "This is of course part of a wider phenomenon – the simple fact of the matter is that at every inquiry where English Heritage has objected to tall buildings on the grounds of their claimed unacceptable impacts on heritage assets, and there have been seven such cases to date, the secretary of state has disagreed."
In his concluding remarks Mr Katkowski highlighted some of the local support for the proposals.
"The position of the Waterloo Community Development Group demonstrates that the perception of local residents is that the scheme would bring more benefits than costs to them. This is the first tall buildings scheme that the group has supported and their support has not been won lightly."
Mr Katkowski also emphasised that the scheme now has the backing of the regime of Mayor of London Boris Johnson, whose deputy mayor Sir Simon Milton wrote to the inspector on 17 April asking that planning permission be granted – "which those with a knowledge of London politics will realise is hugely significant. Such support is not given lightly."
"There would have to be a very compelling and overwhelming reason to turn away all this and to condemn the site to more years of uncertainty. There is no such reason.
"This is another case in which English Heritage has adopted an exaggerated position, accompanied by their frequently encountered fellow traveller Westminster City Council.
"The simple fact of the matter is that ... time and again the secretary of state has had the foresight and courage to say, these concerns are overstated and a more balanced and rounded view must be taken."
Planning inspector Ava Wood will now write a report and make her recommendation to Hazel Blears. The communities secretary is expected to make a final decision in the autumn.
In the meantime the question of tall buildings on the South Bank will be back in the spotlight in June when the legal challenge against Ms Blears' decision in the Doon Street case will be considered by the High Court.