Powerful ministers, political heavyweights and party activists enjoyed the free-flowing champagne and sumptuous surroundings.
It was 2.54am on Friday, October 12, 1984, at the Grand hotel in Brighton.
There was a buzz of activity on the second floor as Margaret Thatcher worked through the evening.
Secretaries were bashing out final drafts, private secretary Lord Butler was still discussing crucial Government business.
Some of the delegates had started drifting off to bed, full of expectation before the Prime Minister's keynote speech the following day.
Then came the explosion.
The 100lb bomb planted by IRA terrorist Patrick Magee ripped through the building, sending a chimney stack crashing through nine floors.
Five people were killed and 34 seriously injured. Some would never fully recover.
The deadly attempt to wipe out the Cabinet was the most audacious attack on the British government since the Gunpowder Plot in 1605.
The political reverberations of the bomb are still felt today and for the people involved the nightmare remains very real.
It ripped through the lives of those who survived.
Lady Sarah Berry lost her husband, Sir Anthony, in the blast and only just escaped from the wreckage.
She was trapped for more than three hours among the bricks and plaster with a broken pelvis.
Her pet Jack Russells, Lucky and Smudge, saved her life by barking for help.
She had been fast asleep in room 328 when the bomb exploded and her bed plunged through two floors.
Lady Berry said: "Normally I sleep on the right side of my husband but because the telephone was on the left and I was expecting a call we decided I should sleep on the left.
"It was the first and only time I did that."
Sir Anthony went downstairs again to say goodnight to some friends - "Then he went into the bathroom to clean his teeth. That's the last time I saw him."
Lady Berry did not find out her husband had been killed until later that evening.
She said: "It was very difficult to get him out and he had to be identified by my stepson.
"I was very sad but I already knew he was dead.
"I feel I had two lives, before and after Brighton.
"Every day since then has been an extra day.
"I know some people feel very guilty when they survive and other people don't but I don't see life like that. You should appreciate the life you have and make the most of it, especially for your family and your children."
Lady Berry had drifted off to sleep when the device exploded and she thought she was dreaming as the bed dropped through the floor.
She said: "I remember a bang and the feeling - falling, falling. It was like Alice in Wonderland falling down and down a tunnel.
"I tried to get back to sleep and tried to get comfortable.
"I remember I had a glass of water next to me but when I went to get it I got dust in my face."
Lady Berry was trapped among wooden girders and rubble.
She said: "I heard all these voices but I had no way of communicating.
"I couldn't understand why they didn't get me. I was shouting out.
"It was a nightmare.
"My prayers changed from wanting to be found to dying quickly. I became very deeply close to God at that point.
"I didn't know what had happened. There was no way you could make contact with the outside.
"It would be so awful dying buried in the rubble.
"I would have done almost anything to be laid out on the beach in Brighton, to die in the fresh air with the sky above me.
"I would have been scared to die alone. I was always alone except for my dogs. I never heard my husband."
At precisely 6.45am, a firefighter was able to saw through a wooden beam crossing her neck and free her.
Lady Berry said: "He finally managed to get his hand on my left shoulder. I remember exactly where. It was just the absolutely most amazing feeling."
Chris Reid, the East Sussex firefighter who found Lady Berry, said: "I thought I heard a dog barking but it was in the distance. I called for a silence. It was quite distinct that there was a dog barking.
"But there was also a woman's voice calling for help.
"I asked her 'What's your name?' and she said 'Lady Berry'. That was not the answer I was expecting and I wasn't sure how to address her."
The ever-faithful dogs had saved her life. And the only consolation Lady Berry took from that terrible night was she was reunited with her much-loved pets. She said: "The fireman came back with a grey bundle under his arm and it was Smudge my dog and I was so happy to see him."
Pamela Pleppert was a chambermaid at The Grand and was responsible for cleaning room 629, where the device was planted.
The pensioner still suffers from the shock of having disturbed Magee and his shadowy female accomplice as they placed the explosives behind a bathroom panel.
She said: "I tried to get in but the do not disturb notice was on the door.
"I went in once and he was there and he said I couldn't come in so I went out again.
"He was in there all the time doing something but I didn't know what it was.
"If I had slammed the door it might have gone off. God, I didn't even know that bomb was in that room - tick tock, tick tock."
The conference was two years after the Falklands War and at the height of the national miners' strike.
The troubles in Northern Ireland seemed to be spiralling out of control with the IRA promising to take the "war" to the mainland.
The country was divided but Margaret Thatcher was in determined mood as she travelled to Brighton to rally the troops.
Her trusted chauffeur, Dennis Oliver, remembers the journey.
He said: "It was one of the highlights of the year and she was going to enjoy it.
"She was quite determined she was not going to give in to the miners."
The conference was a rallying cry for the party faithful.
But with the most senior and powerful politicians in the country gathering in the seaside town it was also a perfect opportunity for a terrorist attack.
Just nine months before the Conservative conference, an IRA arms dump had been uncovered, with a stock of long delay timer mechanisms.
Harvey Thomas, now 65, was the Tory conference producer with the threat of terror never far from his mind.
He said: "We asked the Chief Superintendent of Sussex Police three days before if there was any intelligence of terrorist activities and he said no."
Detective Sergeant Alan Neil, Sussex Police protection officer, said: "There was a risk assessment and it was given as very low. That is what we were all told."
Special Branch had declared a national Bikini Black Alpha alert, one of the highest official security levels, but this crucial information had not, apparently, been passed to Sussex Police.
Harvey Thomas allocated rooms to the guests.
He said: "Apart from Mrs Thatcher and certain members of the Cabinet who needed to be with her on the third floor, it was pretty much a lottery of seeing who would be in what room."
By chance, Sir Donald Maclean, the Scottish party chairman, was given room 629 and even bathed inches from where the deadly bomb had been hidden.
Sir Donald lost his wife Muriel, 54, after she was blown through a wall in the blast.
He said: "At the most, there must have been 19ft from the bathroom when it went off.
"I came to in the rubble somewhere. I couldn't move much. I didn't know where Muriel was at that time."
A parking meter timer had been used to delay the detonation of the bomb by 24 days, six hours, 36 minutes. It would go off in the middle of the night, hours before the Prime Minister would take to the stage for the conference finale.
Television presenter and political correspondent Richard Whiteley was among the guests drinking champagne and enjoying the largess of conference.
He said: "There's always a great atmosphere on the Thursday. Everyone comments 'Hasn't the conference gone awfully well?'
"It's a real party day. There are parties all day and all night and everyone looks forward to the Friday and the leader's speech."
As the revellers chatted and danced into the small hours, Mrs Thatcher was still working.
Mr Thomas said: "She said to me 'I might visit four or five balls and then I might call you between two and three and we might do some more work.'
"My wife was then five days overdue with our first baby girl so I was almost expecting to be woken by the Prime Minister or by my wife to say my baby was on its way.
"But I never expected to be woken up the way I was."
The Prime Minister's private secretary Sir Robin Butler was in room 120 with Mrs Thatcher when the bomb exploded.
Shortly after 2.35am he asked her to look over just one more paper.
Sir Robin, now Lord Butler, said: "I was sat on a chair not looking at anything but thinking how nice it would be to be in bed in ten minutes' time."
As the Prime Minister sat in an armchair with her back to the window, the bomb exploded with devastating effect.
The time was 2.40am. Lord Butler still remembers his first words to Margaret Thatcher after the hotel was ripped apart by the explosion.
"I said to her 'Prime Minister, I think you should come away from the windows.'
"She answered 'I must see if Dennis is all right' and she disappeared in darkness to see Dennis was asleep.
"I had visions of the tribunal saying 'Why did you let the Prime Minister go into this falling building, never to be seen again?
"To my great relief they appeared again, Dennis pulling a pair of grey flannels over his pyjamas."
Meanwhile, in the main lobby Richard Whiteley was chatting to Nigel Lawson's secretary.
He said: "Someone shouted 'Come and have a drink, we're awash with champagne'.
"But I looked at my watch and said 'No, it's ten to three.'
"There was a bang, a big crack outside. I had never heard a bomb but I knew exactly what it was straight away. There was another big crack, louder than the first and that floored us.
"We fell to the floor, we crumpled up in slow motion.
"You could not believe that you were there and this had really happened.
"A lot of people came outside. People seemed to come out in various states of undress.
"No one was speaking. You just had to look and you just could not believe it."
The five people murdered in the bombing were Muriel Maclean, Sir Anthony Berry, 59, MP for Enfield, Southgate and North West Area chairman Eric Taylor, 54, Roberta Wakeham, 45, wife of Tory Chief Whip Lord Wakeham, and Jeanne Shattock, 52, wife of the Western Area chairman.
The bomb was planted by the IRA to send a clear political message to the government.
But the Prime Minister was determined to demonstrate that terror could not shake democracy.
She opened the conference at 9am prompt the next day.
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