Keeping the names of those who sacrificed their lives during the First World War immortalised in stone forever is an honour for those responsible.

As part of plans to mark the Centenary of the Great War, the Commonwealth War Graves Commission (CWGC) is making sure that all of its headstones across 153 countries are in pristine condition.

While many stones are re-engraved, some are past that point and are being replaced.

Of a survey of 470,000 headstones, some 50,000 First and Second World War stones have already been found in need of replacement.

As part of efforts to make sure people are greeted by perfect headstones, the CWGC's production workshop in France had upped its levels from 6,000 per year to 22,000.

Headstone production manager Mike Diaz said the increased target has prompted more staff to be taken on, and for the small workshop to increase its workload to operate five days a week, using three shifts that work virtually through the night.

Mr Diaz, 48, said: "Here in France we engrave all the headstones for the CWGC and basically distribute it to 153 countries throughout the world.

"We are currently engraving 22,000 headstones per year, we came from a target originally of less than 6,000. In 14 months we have increased capacity by some 345%.

"The increase is required because of the deterioration in the headstone, predominantly Portland headstones in coastal areas.

"We had a worldwide survey carried out and its basically highlighted that we have something in the region of 70,000 headstones in a critical condition where the names and the numbers were becoming illegible."

He said it is vital to the commemoration of the war dead to make sure that their headstones are kept in excellent condition.

"The reason why we're here is to commemorate those who fell in the First and Second World Wars - to honour their names and to never allow their names to be forgotten.

"We are now coming up to the centenary of the First World War and there are very few people that can remember that.

"It's difficult to make people aware of that fact and as their names are eroded by time and weather it's an honour to go back and say, 'right let's change the headstone'.

"It's an honour for all of us."

The workshop uses machines that take a computer drawing of the inscription for a gravestone, then engrave it into stone using high carbon tungsten steel bits.

Mr Diaz said information is extracted from the CWGC's database to make sure the right details are on each headstone, with the process closely monitored by the workshop's staff.

"We basically draw the picture and transfer that from one secure database onto the machines," he said. "Then we start to engrave.

"The engraving is done by machines, however it's not just press the button and away it happens. The machines have to be manually loaded, we have to merge all the documents together effectively.

"We have to make sure the inscription is correct, we have to make sure there are no errors. We have to check every single headstone."

Each headstone is checked three times before it leaves the workshop he said, to make sure that each is correct and going to the right place.

And even the way the CWGC engraves its headstones is special, he added.

"Everyone else engraves at 45 degrees, it's a standard cut. We engrave at 60 degrees.

"As you look at a headstone, generally you stand about 6ft away out of respect, and so as you scan the rows you are actually at 45 degrees therefore there would be no shadow, so at 60 degrees there is, and you can read what it says.

"We're the only organisation that engraves at 60 as far as I'm aware."

The commission uses 34 different types of headstone, and up to four different types of stones per marker shape.

But once different inscriptions are added, along with cap badges, religious symbols, and military honours such as VCs, the number of different options run into the hundreds of thousands, he said.

But Mr Diaz said the mammoth nature of the task did not put off the small team who work in the little-known factory in France.

"All the staff are here because they want to be here, because we all believe it's right and fitting and the work that we do is just totally correct. We're honouring those who fell.

"Everybody here believes in what they are doing here. We're engraving names into stone which is quite a permanent thing.

"However without the fallen people, the soldiers and civilians that gave their lives, we wouldn't be here.

"The first World War changed humanity completely. It changed the UK, it changed Europe, and it will never be repeated. We must honour them."