The King has marked the 50th anniversary of the Birmingham pub bombings by sending a personal message praising the relatives of those killed and survivors for their “exceptional strength of spirit”.

Hundreds of people, including relatives of the 21 people killed in the twin IRA bomb blasts on the night of November 21 1974, gathered near a memorial close to New Street station on Thursday for a service including a minute’s silence.

The service also saw the names of those killed read out, as their loved ones’ placed roses on the memorial.

As well as those killed, more than 200 were injured when bombs exploded minutes apart in the Mulberry Bush, at the foot of the Rotunda building, and the Tavern in the Town in New Street, in what remains the worst unsolved terrorist atrocity committed in Great Britain.

Birmingham pub bombings 50th anniversary
The Duchess of Edinburgh during the service (Jacob King/PA)

The King’s message, read out on his behalf by The Duchess of Edinburgh, said: “As you come together to mark 50 years since the terrible events of 21st November 1974, my wife and I would like to take this opportunity to say that you, and all those affected by this dreadful attack, remain very much in our thoughts.

“Today we remember the 21 people who lost their lives so cruelly and all who were injured, many of them grievously. We also pay heartfelt tribute to those who rushed to their aid.

“What happened on this day 50 years ago was one of so many dreadful tragedies in a devastating period that touched us all, many of us very personally.”

Birmingham pub bombings 50th anniversary
Members of the public watch the memorial service in 1,000 Trades Square (Jacob King/PA)

The message added: “To see the brave strides forward that have since been made towards lasting peace and meaningful reconciliation, and the close bonds of love and friendship which now bind this city together, makes me exceptionally proud and thankful.

“I must also express my sincere admiration for you, the people of Birmingham, who have lived so courageously with the grief of that day and the days that followed.  

“Your exceptional strength of spirit and resolve has truly embodied this wonderful city’s elemental motto: Forward.

“I am very sorry that I cannot be with you all today, but my thoughts, prayers and very best wishes remain with you all as you mark this saddest of days.”

Further tributes are planned to mark the anniversary this weekend, with Aston Villa planning a minute’s applause in memory of the victims at half-time of their match against Crystal Palace at Villa Park.

The Library of Birmingham is also being illuminated on Thursday night to mark the 50-year anniversary.