One of the most notorious routines in Barlinnie for more than 120 years was the practice of slopping out. As in most other prisons, inmates had to queue each morning shortly after 6am to empty pots of human waste into a giant sink.

It was a humiliating and degrading experience for all concerned - both prisoner and prison officer alike. In 1993 the European Committee for the Prevention of Torture warned that Scotland needed to end the practice of forcing prisoners to use a bucket at night as a toilet.

The practice had been abolished in prisons south of the Border by 1995 but Scotland was slow to follow suit. That was until Robert Napier arrived on the scene.

In 2004 a court ruled that the 42 days he had spent on remand in Barlinnie slopping out each morning was a breach of his human rights. He had been arrested after failing to appear for trial on robbery, assault, and abduction charges.

Robert was awarded £2450 for the effect the prison conditions and slopping out had on his health. Hundreds of prisoners came forward as a result and millions of pounds was paid out in compensation over the next 13 years.

Read the full series here: Barlinnie: The story of Scotland's super-prison

The case forced the prison service to spend more than £100m on emergency measures to modernise jails. Slopping out was still in practice in Barlinnie in 2002 when it was finally ended. Now all the cells have flushing toilets.

Glaswegian Charles Campbell worked for 15 years as a prison officer at Barlinnie before retiring on ill health in 2004. Charles, now 65, had previously served for ten years in the Queens Own Highlanders in trouble spots like Northern Ireland and the Falklands.

One thing that the army didn't prepare him for was the overpowering smell that pervaded Barlinnie at the time, due to slopping out.

Charles said: "Even though I've been retired now for 20 years I can still feel and taste that smell. "Every morning at 6:15 am you had 300 men standing with plastic containers of urine and excrement from the night before.

"It was degrading for both them and the staff and the stink was unimaginable. "Even when I left in 2004 most of the prison was still slopping out as very few of the cells had flushing toilets.

"Any time I brought visitors to Barlinnie the first thing they would always notice was the smell left by the slopping out."

Charles says that many of the prisoners would wrap their excrement in toilet paper and then throw it out of their cell window into the exercise yard - called bombs. Teams of prisoners then had to be sent out each day to clear the mess up.

He added: "The smell was particularly bad at the weekend when they could be locked up for up to 14 hours.

"The abolition of slopping out was long overdue. It was particularly bad for female prisoners who had to watch as the prisoners slopped out.

Charles added: "Nothing was allowed in the cell to take away the smell.

"Slopping out was disgusting. It wasn't fair to anyone, and the smell was also unpleasant for visitors. You never forget it."

Charles now lives near the site of the new prison and says the closure of the old Barlinnie was long overdue. He says the most important thing with the new jail, will be the quality of the in-cell sanitation.

He said: "If you treat prisoners properly and with respect you get it back. That means they are more open to change and rehabilitation. That way everybody benefits."