Former House of Commons speaker Baroness Boothroyd has told the House of Lords that the status of the Palace of Westminster will be diminished by a "building frenzy" of high-rise towers around Waterloo and the South Bank.
"My Lords, shortly before the summer recess, and almost unnoticed, UNESCO announced its intention to put the Palace of Westminster on its danger list of world heritage sites," said Baroness Boothroyd on Wednesday night.
"It was not referring to the urgent need to repair and restore the fabric of this building.
"It was alarmed by the increasing number of high-rise tower blocks being built and planned along the South Bank."
She continued: "English Heritage, Westminster City Council and other cultural bodies have registered their dismay at the dangers posed by the loosely controlled planning laws which allow the South Bank to become London's second-biggest building site, which can no longer be ignored.
"The growing number of tower blocks being planned for the other bank jeopardise the status and integrity of this Westminster site on which this palace and our Parliament stand."
The former Commons speaker told peers: "If the redevelopment of the South Bank continues at its present rate, this ancient seat of government will be diminished.
"The Government have the power to prevent it but, unfortunately, have refused to use their authority. If this continues, we face the prospect of a wall of high-rise, high-density tower blocks stretching in a jagged line from Waterloo to Vauxhall.
"If that is allowed, it would ruin the dominant setting that this place has enjoyed for centuries on this stretch of the river.
"Waterloo nearby is identified by Lambeth Council as a 'major development opportunity'. The Mayor of London agrees.
"Noble Lords have only to look at the architects' illustrations for the redevelopment of the Shell site and the adjacent Elizabeth House project to realise the enormous size and scale of what is planned."
She warned: "I am afraid that we are approaching the point of no return. So far, the Government have paid lip service to our heritage and have let the building boom rip.
"I understand that the Tower of London was lucky to avoid a similar danger notice. If this place is confronted by citadels of glass, steel and concrete on the other side, UNESCO has no choice but to tell the world that we are failing to meet our obligations. It would be a shameful blow to this country's reputation, a dereliction of the Government's responsibilities and a betrayal of future generations.
"Nothing like this has happened in continental Europe and it must not be allowed to happen here.
"The more that I look at this, the more amazed I become. Here we are, cherished throughout the world but at the mercy of local councils and developers who enjoy the Government's wholehearted support.
"What does UNESCO want? It wants the Government to strengthen the planning laws and create buffer zones between the high-rise development to protect this Westminster setting.
"Mr Eric Pickles, the local government Secretary, sees no harm in building a new, eight-tower cluster around the existing Shell building across the river – one of them 37 storeys high. Boris Johnson also gave his blessing. It is a far cry from when he defended Westminster's heritage before he became Mayor of London. He changed his tune when he was elected; he should do so again before he resumes his parliamentary career."
Baroness Boothroyd added: "The borough councils on the south bank are willing participants in the building frenzy, which is the biggest, I understand, for 300 years.
"The councils were supposed to discuss the new framework for major projects on their side of the river that affect this place; but they have not met for a year because, I am told, there is no prospect of them agreeing anything."
Labour's Baroness Andrews – a former chair of English Heritage – described the redevelopment of Elizabeth House in York Road as "a case study of some of the real planning challenges that we have in London at the moment".
She said: "As statutory consultees, our challenge to that building was extremely important, and we did not do it lightly."
Lady Andrews continued: "At its meeting in Doha in June, UNESCO recommended that the UK should find a way of ensuring that the [Elizabeth House] proposals were not approved in the current form and were revised in line with the concerns expressed.
"Lambeth has come forward with the revised proposal but I am assured, and this is the reason why English Heritage is sustaining its objection, that this second proposal is very much unchanged from the first. It is very similar to the first, so we still have a big problem.
"That is important because, when it comes to consider it in February, UNESCO will look to see whether the application has changed. If it decides that the world heritage site should be put on the blacklist, we will be in serious trouble.
"We have the reputation as leaders in the world of heritage. If we cannot take care of our heritage, how can we conceivably expect the other 191 countries that signed the convention to do so?"
Conservative Lord Cormack added his voice to the debate, telling peers that "we are threatened with buildings that will destroy the skyline around this great complex of buildings – the Palace, the Abbey and St Margaret's – in the way that the skyline has been destroyed around St Paul's.
"Anyone who has a real feeling for historic buildings only has to look at those great Canalettos and weep internally at what has gone. We could have developed as a vigorous city without raping the skyline.
"I hope that the call to arms that has been sounded tonight by the noble Baroness, Lady Boothroyd, and echoed by the noble Baroness, Lady Andrews, will be heeded."
Labour's Lord Tunnicliffe said that communities secretary Eric Pickles had "abdicated his responsibility to make a national decision about a national issue" by refusing to 'call in' the redevelopment of Elizabeth House for a public inquiry.
He said it was "unfair" to put the burden of decision-making on Lambeth Council: "What do I mean by that? There is no criticism of Lambeth in those words, but Lambeth's responsibilities are to the citizens of its borough – to their narrow concerns.
"It has strong concerns and views as to why the project might be sensible and might be favoured, but it does not have responsibility for a world heritage site.
"It is poor, as all local authorities are, and it cannot afford a big legal battle with a rich, powerful developer."
Replying to the debate, Government minister Lord Gardiner of Kemble said: "The London skyline has outstanding artistic and architectural merits in its own right. Indeed, many new developments, from the Gherkin to the Shard, can be sensitive and respect those iconic buildings that long preceded their construction.
"Turning to planning, which is very much part of this debate, the Government believe that the best way to address planning proposals is to ensure existing policy and guidance are properly applied by those who make decisions.
"Our country has a strong planning system which provides for heritage protection, and the protections for world heritage properties in the United Kingdom, including in London, have been strengthened in recent years."
He added: "Planning decisions will, quite rightly, be taken at the local level, and the Government will use their power to call in an application for their own decision only in particular circumstances."
Lord Gardiner continued: "The noble Baroness, Lady Andrews, and other noble Lords, however, spoke of the proposed development of Elizabeth House at Waterloo. The decision is the responsibility of Lambeth Council, and the recent High Court case heard by Mr Justice Collins confirmed that that is the case.
"As the noble Lord, Lord Tunnicliffe, mentioned, Lambeth Council will review the planning application in December. I know that the council is fully aware of its obligations and the balance that needs to be struck.
"Finally, the Shell Centre development on the South Bank is currently the subject of a High Court challenge.
"It would obviously be impossible for me to comment on an issue that is now a matter for the court."