Heather's parents, Elizabeth and Richard Cheetham, along with her little sister June, were going on holiday.

It was an annual family ritual they all looked forward to, going on a trip to the island in the Irish Sea and staying at a seafront guest house in Douglas.

Although Heather, 69, wasn't joining this time and instead, seeing off the family alongside her husband Reg, now 79, she knew one of the highlights of their trip would be somewhere they'd all visited before - the newly opened Summerland.

A dazzling building designed to hold 10,000 tourists, the Summerland leisure complex was everything you'd want from a seaside holiday under one roof - dance halls, bars, restaurants, a bingo hall and five floors of amusement arcade games.

It was made all the more impressive by a cavernous glass structure that covered the building, a dome that made it seem 'sunny' all the time, no matter what the weather.

On Thursday 2 August 1973, the Cheetham family visited the complex. They never made it out alive.

The family, alongside 47 other people, including 11 children, died after a fire engulfed the entire building in under an hour in one of the biggest fire disasters since the Second World War.

"We were watching TV and we'd seen there had been a big explosion," Heather recalls.

"The shock of seeing it on television like that… once the fire took hold, the building came down so quickly, everyone thought it was an explosion.

"A number appeared on the screen and we started dialling, but it took 12 hours for us to get through and they still couldn't tell us whether my family was alive or dead."

The next week, the newly married Heather and Reg lived through what they describe as a "horrendous nightmare".

"I had a sinking feeling I would never see them again, because if they could've got to a phone, they would have called."

Eventually, they were told of the deaths of Elizabeth and 13-year-old June.

Reg was asked to find the dental records of his father-in-law Richard as his body wasn't even recognisable.

All three died of burns, according to the coroner's office.

"A witness at the time said my mother and sister had gone into the building to collect some bingo winnings, and when the fire started, my dad ran into the burning building to try and save them," says Heather.

"It's a horrible thing to happen to anybody."

The main causes of death for the victims were suffocation, carbon monoxide poisoning, burns and multiple injuries from falling.

A total of 102 people were injured - almost all were holidaymakers who had come for a break from the north of England.

The fire was thought to have been started by a discarded cigarette.

"We coped because we were newly married, we had a new life," says Heather.

Reg adds that the couple stuck to their daily routine and tried to carry on as best they could.

"But I remember about two months after it happened, I went to see my doctor to ask for help, and he said, 'is your marriage OK?'

"I had to say… 'I'm not here for my marriage, can you help me with Summerland?'"

The couple, who now live in the Wirral, Merseyside, still find it painful to talk about the subject to this day - but it's the findings of an investigation into the inferno that stays with them.

'They said no villains' were responsible

On 24 May 1974, a report was released cataloguing a series of failures regarding the Summerland disaster, from the design of the building, to the fire safety regulations.

No individuals or groups were singled out to blame for what happened, and all the deaths were ruled as "death by misadventure".

The report said the accident was down to "human errors, a reliance on the old-boy network and poor communications".

Dr Ian Phillips of Birmingham University, who documented the disaster in a report, says "[the ruling] was wrong".

"They said in it that there were no villains and I believe the coroner was influenced by that line and that's why the ruling was 'death by misadventure'."

A death by misadventure verdict is defined as "a death that is primarily attributed to an accident that occurred due to a risk that was taken voluntarily". In other words, those that died were held to have been at least partly responsible for their own deaths.

The Summerland Fire Commission who investigated the incident, listed several reasons for the huge loss of life:

The evacuation of the building was delayed;

No fire alarm rang inside Summerland, even after the entire building was in flames;

The fire brigade was not called for 21 minutes after the fire began;

The internal layout didn't take into consideration fire escape routes;

There was misuse of new building materials - Oroglas, Galbestos and Decalin.

What was clear from the report was just how many things had gone wrong - both on the night, and from the day the ideas for the complex were drawn up by James Phillipps Lomas and a team of architects hired by Douglas Corporation to create the leisure centre.

One element focused on was the Oroglas material. It was used by the architects for its 'transparent effect' to give the building its greenhouse look - but didn't satisfy building regulations on the island.

At the time of building, the law was waivered.

Dr Phillips explains that while the waiving of building regulations isn't entirely uncommon, other measures are usually put into place.

"Compensatory measures are usually made to make up for any potential shortcomings where fire safety was concerned - but not in this case."

The list of failings in the report continued. The open design led to the fire spreading at speed in all directions, according to the investigators.

The person in charge of the control room on the day of the fire who needed to sound the alarms throughout the building in the event of such a blaze didn't know how to operate the fire alarm panel.

No staff called 999 when the fire began, and the first calls came from a local taxi firm 21 minutes after it erupted - because staff had not been trained in emergency evacuation procedures. The external wall made of Galbestos wasn't fire resistant.

Half a century later, the ruins of the site, now derelict, are still standing.

'An insult to blame those who lost their lives'

An Apologise For Summerland campaign has been launched to fight for the 'death by misadventure' verdict to be overturned.

They say their support is growing in numbers, from cross-party MPs and organisations such as Grenfell United - who say the similarities are "chilling" between the Isle of Man disaster and Grenfell tower.

A spokesperson for the campaign told Sky News: "Summerland was sold as a holiday paradise. Instead, it was a death trap and yet no one was held accountable for the tragedy or has apologised for what went wrong.

"We are asking for an apology for the blatant disregard for basic fire safety, and a recognition that the 'death by misadventure' verdict was inappropriate.

"We feel it is an insult to blame those who lost their lives in a fire that was no fault of their own. Our campaign's demands are not hard to accomplish, but they would help to heal the wounds of the past."

In an interview with Sky News, MP John Madders, who has pushed for a public inquiry in the Commons, said it seemed like "everyone on the Isle of Man wanted to forget about it and the families deserve proper recognition".

Mr Madders said: "The way the aftermath was handled was bad."

"The verdict was wrong and it can't stand - if there's an acknowledgment that that was inappropriate that would help people cope with this.

"If you look at the multiple failings in the inquiry, it's staggering that no one was held accountable for this.

"It's an offensive verdict for those who have lost someone - almost implying that someone who went on holiday were somehow responsible for fire safety."

The Chief Minister of the Isle of Man has since made a statement to the island's parliament to mark the anniversary.

Alfred Cannan MHK said: "There were inadequacies, failings and lapses identified by the Commission, and that had matters been addressed differently, some of the loss of life at Summerland may have been prevented. 

"The causes and contributing factors are individually serious. Collectively they resulted in a tragedy. I am sorry. Sorry for the pain and suffering felt by everyone affected by the fire and sorry for the failings that could have prevented such a tragedy.

"The 50th anniversary of the Summerland fire is the right moment for this government to offer an apology for the suffering caused by the wrongs of the past." 

It is the first apology ever given by the government, something the campaign considers a win.

But the fight continues to get the verdict overturned.

'We'll fight to the end for this'

Heather and Reg say their daughters, Vicky and Jane, began finding out what really happened to their grandparents in their teenage years, and it was clear the legacy of what happened is far from forgotten.

"They took it in their stride, but it was a shock to them. Then a few days later my daughter started crying and she said she realised her loss," said Heather.

"Vicky wants to know more about her aunty June and nan and grandad, she backs us all the way, they believe it needs recognition.

"When the campaign became public, the government said, 'why now'?" she says, fighting back tears.

"Time shouldn't matter. It happened. We want recognition for the people who died. They weren't doing something they weren't supposed to be doing. Deep down, I know my sister would've wanted us to do something.

"We'll fight to the end for this - and it hasn't ended for us, why should it for the Isle of Man?"