Families of the 52 people killed in the July 7 bombings marked the fourth anniversary of the atrocities by unveiling a commemorative plaque in central London yesterday.

Families of the 52 people killed in the July 7 bombings marked the fourth anniversary of the atrocities by unveiling a commemorative plaque in central London yesterday.

The Prince of Wales joined Prime Minister Gordon Brown and other political leaders at a ceremony in Hyde Park - four years to the day after the bombs ripped through London's transport system in 2005.

A monument honouring the dead was built to incorporate 52 stainless steel columns, or stelae, each representing one of the victims of the terror attacks.

Each column is unique and they have been grouped together in four clusters, reflecting the separate locations of the bombings - Tavistock Square, Edgware Road, King's Cross and Aldgate.

Four suicide bombers detonated their rucksack devices near these locations on the morning of July 7, 2005, killing 52 people and injuring hundreds of others, some seriously.

The family of Helen Jones, a young Scottish accountant killed in the blast near King's Cross, published a moving poem expressing their grief to coincide with the anniversary.

Ms Jones' stepfather David Gould composed the piece - entitled "Fourth Year Without Helen" - and posted it on an online memorial site. A statement before the verses recalled Ms Jones, who was murdered at the age of 28, as "a warm-hearted and beautiful person who it was a privilege to have known and loved."

It added: "She gathered many people to her in a unique way and never lost touch with any of her many, many friends.

"She was dearly loved by friends and family and sorely missed when she was killed."

The family intended to visit their lost daughter's grave yesterday "and think of heavy hearts that mourn / for all who died that day", the poem added.

Raised near Lockerbie, Ms Jones moved to London after studying divinity at Aberdeen University and was enjoying life as a chartered accountant when tragedy struck.

The morning of her death she sent a text message to her boyfriend, Clive Brooks, before boarding a tube train on the Picadilly Line.

The train was just outside King's Cross station when the bomb went off, killing most of those inside.

Mr Gould and his wife Liz Staffel, Ms Jones' mother, have led many tributes to their daughter during the four years since her death.

In 2006 the couple launched a scholarship to pay for pupils from Lockerbie Academy to follow in Ms Jones's footsteps and become accountants.

They also helped to compile a memorial book for those affected by the July 7 attacks.

Friends of Ms Jones have honoured her memory by organising a special collection in aid of the Glasgow City Mission, where she worked as a volunteer.

At the ceremony in London yesterday, a stainless steel plaque naming all those who died was unveiled at the memorial site between Hyde Park's Lover's Walk and Park Lane.

Saba Mozakka, 28, one of six relatives on the memorial's project board who helped create the monument, said: "We think it is truly incredible and reflects the importance of the people commemorated.

"One of the fantastic things about the monument is that it reflects the individual and the collective and shows the connectivity of events."

Ms Mozakka's mother, Behnaz Mozakka, 47, a biomedical officer, was killed on the Piccadilly Line train while commuting to work.

Former London mayor Ken Livingstone was among the 700 invited guests, who included politicians, survivors and victims' relatives.

He praised the striking design for the memorial, saying: "I think it's just exactly right.

"Often, it's very difficult to do something like this and get it right, but I think everyone has done a great job."

Speaking about the actual day when the devastating bombs exploded, Mr Livingstone said: "On the day, what drives you is the work that's got to be done, but, in the weeks and months afterwards, I met many families at various memorials and it was all incredibly painful."