Charles mourns with families at 7/7 memorial

As the names of the 52 bus and Tube passengers who perished on the 7 July 2005 echoed across Hyde Park yesterday, the first rain drops began to fall. By the end of the minute's silence torrential rain pelted down on the families and survivors who had gathered to mark the unveiling of a memorial to the dead.

It seemed, they said, a fitting sign of the grief that still affects so many four years after they lost family and friends to a senseless act of violence.

Yesterday's service to officially open the London memorial – a series of 11ft stainless steel columns signifying each one of the victims – was simple and dignified as the Prime Minister Gordon Brown and leaders of the opposition parties stood without ceremony among those affected by the terrorist attacks.

For the families the most poignant moment came when they formed a slow procession to lay a white and red rose – signifying peace and love – by the plaque that bears the names of those who died to the haunting sounds of Remembrance, a specially commissioned piece by composer Christian Forshaw. Tears, held back until then, began to flow.

Praising the "resilience and fortitude of the British people", the Prince of Wales – who with the Duchess of Cornwall laid a wreath – said he had some small sense of what the families were feeling after the loss of his great uncle, Lord Louis Mountbatten, in an IRA bomb. "I can only too well recall the intense despair and many other emotions that I experienced when my beloved great uncle, Lord Mountbatten, was murdered by terrorists 30 years ago next month, together with my godson, his grandmother and the boatman's son," he said, adding: "Everyone has their own way in responding to trauma, grief, injury and bereavement, but I do pray that all those touched by violence everywhere will eventually find peace again."

Relatives praised the simplicity of the memorial. Costing nearly £1m, it has 52 columns grouped together in four clusters, reflecting the separate locations – Tavistock Square, Edgware Road, King's Cross and Aldgate – where the four suicide bombers killed 52 and injured hundreds more.

As well as Mr Brown, Tory leader David Cameron, Liberal Democrat leader Nick Clegg, London Mayor Boris Johnson, humanitarian assistance minister Tessa Jowell and senior figures from the emergency services and representatives of other organisations attended the unveiling.

As they waited for the dignitaries to arrive many of the relatives and survivors wandered through the towering columns, running their hands over the metal surfaces.

"I felt more emotional today than I expected. You can walk right into the middle of the memorial and touch the pillars.

"It brings you closer to the people that died. The fact that it is ground level gives is a sort of intimacy," said Kathy Lazenbatt, who was the last seriously injured person off the Edgware Road train and said that yesterday was about remembering Laura Webb and Jonathan Downey, who died beside her.

They would not be forgotten, Ms Jowell promised the families during the ceremony: "They are immortal in your hearts and now immortalised in this place, a place of great beauty but also a place of great pain."