Sixteen miners, some just aged 16, lost their lives on that fateful March day in 1962 when an explosion ripped through the Union Seam at Hapton Valley Colliery. A further 21 people were left seriously injured.
Always known as 'Happy Valley' that tragic day was to change all that.
This year marks the 59th anniversary of the tragedy that has never been forgotten in Burnley by the community and also the children and grandchildren of all the victims.
A memorial service is held annually in Burnley Cemetery and a memorial stone was cast there with all the victims' names on, thanks to the efforts of the Hapton Valley Mining Disaster group.
In 2019 the Hapton Heritage group unveiled a stone on Hapton Recreation peace garden. And this year a new memorial stone has also been erected outside Burnley Library.
Hapton Valley Colliery began life in 1853, when two shafts sunk in an area, which was well proven for coal – there were scores of shallow workings alongside the Habergham Brook and in the sides of Hambledon Hill.
It became known as Spa Pit for a while because of a mineral spring close by. Output was around 600 tons of coal a day, which was dug from the face by miners with picks and shovels. Around 1910, work began on two new shafts number three and four, one more than 500 feet deep.
There was a major emergency in 1957 as a new seam was being opened out, when large quantities of water burst through the floor – at the rate of 700 gallons a minute – and caused extensive flooding and it happened again in 1964.
Finally in 1981 the National Coal Board announced that the colliery was to close. In the four decades since then the site has become overgrown and used as a dumping ground for rubbish and, intriguingly, hundreds of old tyres.
It was seeing this heartbreaking sight that motivated the Northern Monkeys group to roll up their sleeves and transform the area into a proper memorial ground. And, after weeks of back breaking work, they have cleared the area and created a unique woodland memorial.
Followers of the Northern Monkeys, an explorers and conservation group launched last year by pals Damion Whitton, Bruce-Lee Knowles and Chris 'Kipper' Taylor, pitched in with offers of help, resources and donations.
Local companies, including BooHoo and MKM Builders. also made donations when they heard about the project.
And Burnley Council helped with the mammoth task of disposing of a large quantity of the tyres.
They kept some of the newer tyres which they have turned into mine cart style flowerbeds, an idea Bruce came up with.
And each of the 'carts' has a plaque bearing the name of one of the victims or someone connected to the pit.
Damion said: "We originally came to the site to look at the remains of the mine and to search for fossils, but when we saw what a state it was in we decided to try and do something to improve the area.
"The help we have received from so many people has been amazing. Once people found out what we were trying to do they wanted to help."
Several people have already been to visit the site, including a number of relatives of victims of the disaster.
Damion said: "They really liked what we have created here."
Among those honoured at the site are nurse Maud Waggett who, on the day of the disaster, donned overalls and helmet and went to the coal face along with stretcher parties to give morphine to the wounded and dying.
A flowerbed has also been planted in memory of Richard Fawcett, a manager at the pit who died during a disaster there in the 1800s.
The site has also become a haven for wildllife thanks to several bird boxes made and donated by supporters of the Northern Monkeys.
As the site is quite difficult to reach the monkeys are hoping to hold talks with Burnley Council to look at the possibility of making it more accessible.