A minute's silence has been held in Brighton to mark the 30th anniversary of the IRA bombing of the Grand Hotel.
Five people died and 34 were injured in the attack aimed at prime minister Margaret Thatcher and her cabinet.
Conservative Party members were staying at the hotel during their 1984 party conference in Brighton.
Prime Minister David Cameron said: "As we remember today those killed and injured in Brighton, we must renew our vow that terrorism must never win."
The flag on the hotel roof is being flown at half mast, with others around the hotel removed as a mark of respect for those killed and injured.
Staff joined the silent tribute around a plaque in the hotel lobby which was unveiled by former Conservative minister Lord Tebbit, who was seriously injured in the blast.
Mr Cameron added: "On a night of unspeakable horror, IRA terrorists tried to wipe out our country's democratically-elected government.
"I will never forget those shocking images as members of the emergency services scrambled over the rubble to rescue those wounded in the blast.
"But I also remember Margaret Thatcher's defiant response later that day.
"She declared Britain will never be cowed by terrorists and said their sickening attempts to destroy our democracy would fail."
Brighton Bombing dead
- Anthony Berry
- Roberta Wakeham
- Eric Taylor
- Muriel Maclean
- Jeanne Shattock
Andrew Mosley, general manager of the Grand Hotel, said: "It is an opportunity to remind the staff and ourselves of what happened 30 years ago on that day.
"To reflect on what it must have been like for our colleagues at the time and to remember those who lost their lives, those who were injured, the community in Brighton that was so badly affected, and members of the emergency services who were called to the blast."
Patrick Magee, who planted the device, is planning to take part in a discussion following a screening of the documentary Beyond Right & Wrong at The Old Market in Hove.
Lord Tebbit was severely injured and his wife Margaret was left paralysed from the neck down following the blast.
He said: "I think about it every day in the sense that I look at my wife who was sentenced to life imprisonment in a wheelchair."
Lord Tebbit said he had nothing but contempt for Magee, who was given eight life sentences at the Old Bailey in 1986, with a recommendation he serve a minimum of 35 years.
He was released in 1999 under the Good Friday Agreement.
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