In the next few months people will start moving into the luxury new flats at the £400million Islington Square development – paying north of £700,000 for a one-bed. John Tythe and his mates at the London Test Section (LTS) used to sleep there free of charge.

Islington Gazette: Workers getting to grips with the machines. Picture: LTSSACWorkers getting to grips with the machines. Picture: LTSSAC (Image: Archant)

The old General Post Office building, hidden behind Upper Street and accessed via Studd Street and Almeida Street, was bought by Cain and Sager Group in 2003 and the old Royal Mail sorting office was demolished and rebuilt - following major protests by workers.

The 500,000sq ft development includes 263 homes - 94 of which will be affordable - as well as serviced apartments, shops, restaurants and leisure facilities.

One of the original Edwardian buildings is still there and used to be an engineering building, where the LTS was based, alongside the London Materials Section and the GPO factories.

It opened in 1906, and employed thousands of people at one time, even having its own one-way system within the estate.

Islington Gazette: Computers from the old LTS site. Picture: LTSSACComputers from the old LTS site. Picture: LTSSAC (Image: Archant)

John, 69, "owes his very existence" to the building. His mother and father met while working there, she in the factory and he in the GPO store.

"All of my family worked there," John, now living in Cardiff, told the Gazette. "I lived in Linton Street off New North Road. My dad said to me when I was 16: 'What do you want to do?'. I told him I didn't know and he said he'd get me a job with the LTS. He said: 'I watch them all day and they don't do a stroke'."

"Many families relied on Studd Street for their livelihood. Apart from my mum, dad and myself, my brother was also in the factory plus two aunts, an uncle and a cousin.

"Towards the end, my step dad was also there. Just in the LTS, there were fathers, mothers, sons, daughter, brothers, husbands & wives. It was a good place to be!"

Islington Gazette: A worker on the phones. Picture: LTSSACA worker on the phones. Picture: LTSSAC (Image: Archant)

When the split came between the Post Office and BT they had lots of buildings and divvied them up. The Post Office got Studd Street.

To this day John says he dreams about the "tall building with staircases in all six corners". And that's little surprise. The LTS used to test rubber gloves for electricians and the fire brigade. When the site closed in 1985 John bought the company, renamed it Safeglove, and still runs it to this day in Wales.

"I paid £60 for it," he said. "Now 34 years it's been going. It pays for the cruises."

He and his old colleagues still meet up every three months at The White Hart in Upper Street to talk about the good old days. And as you can imagine, they've got some stories.

Islington Gazette: Staff outside the building. Picture: LTSSACStaff outside the building. Picture: LTSSAC (Image: Archant)

"We had about 230 people in my section," he said. "People used to come from all over London to work there, and Essex. We had a 24/7 restaurant, and a bar. Although they had to close the bar in the early 1980s because the postmen were drunk when they went on their rounds.

"They'd only have a few pints from lunchtime until 5pm when they did their collections. I suppose it made life bearable."

John hasn't been back since the site was redeveloped, but has been invited down and hopes to have a look around, though he expects it to have changed beyond recognition.

"£700,000?," he chuckled. "We use to sleep there for free."

Islington Gazette: Islington Square in Upper Street. Picture: Sager GroupIslington Square in Upper Street. Picture: Sager Group (Image: Archant)

The man who takes old workers around is Chris Dunn of Cain.

The developers are keen to keep some of the heritage of the site, and the old Post Office fronting onto Upper Street has been renovated as a shopping palisades with the old decor intact.

The new building that has replaced the old Northern District Office was also designed as a modern version of the Edwardian engineering building it now stands next to.

Speaking of the site's history, Chris told the Gazette: "Prior to opening, the site was a saw mill that prepared timber for the houses. I believe Royal Mail or the Crown Estate had spent 20 years putting the site together.

Islington Gazette: Islington Square in Upper Street. Picture: Sager GroupIslington Square in Upper Street. Picture: Sager Group (Image: Archant)

"Of course it wasn't just post in those days. The Royal Mail was also known for giro bank, and administration. In the 1960s when BT came about it did research into telecommunications.

"It also had one of the largest 24/7 restaurants in the country, I think, which catered for the workers. There was a gardening club, a snooker and billiards room..."

The site also contained post-production facilities and even an anechoic chamber in an old BT acoustics lab. And in 1990 Esther Rantzen's Childline opened offices on the site, with Princess Diana cutting the ribbon.

Islington Gazette: Worker Steve Ruston in the paints lab. Picture: LTSSACWorker Steve Ruston in the paints lab. Picture: LTSSAC (Image: Archant)