A £1 billion upgrade of the Warrior armoured vehicles was announced at the end of last year after concerns were raised about their safety.
Under the improvement scheme, hundreds of the vehicles were to be fitted with a new armour mounting system to allow them to be fitted with different types of armour, the Ministry of Defence announced.
The Prime Minister and Defence Secretary made the announcement last October, revealing plans to fit the Warriors with an improved turret and new, stabilised 40mm cannon, enabling them to fire more accurately while on the move.
It came after fears about the safety of the Warrior were raised when one was involved in an incident in Iraq in April 2007 in which four soldiers were killed when a bomb ripped through the unprotected underside of their vehicle.
Wiltshire Coroner David Masters said at the inquest into those deaths that better protection was needed for troops serving in Iraq and Afghanistan.
He told the inquest in Trowbridge that he planned to meet then Armed Forces minister Bob Ainsworth to recommend that the armour issue was dealt with speedily, adding that he intended to "seek confirmation from the top that something was being done".
The upgrade to the vehicles announced last year at Lockheed Martin UK in Bedford, the company awarded the contract to carry out the improvements, is intended to extend the service life of the vehicles through to 2040 and beyond.
David Cameron said at the time: "We made difficult decisions in the strategic spending review so we could spend money on important equipment like this.
"It's a £1 billion investment - 90% of the jobs and the work are going to be done here in the UK. That's good for the economy, it's good for our Armed Forces but only possible because we made difficult decisions."
He added: "It means we are now able to ensure our soldiers have greater flexibility and firepower with these upgraded armoured vehicles. Warrior has performed outstandingly well in Bosnia, Kosovo, Iraq and now Afghanistan, and this programme will enable it to remain effective to the 2040s."
The head of the Army, Chief of General Staff General Sir Peter Wall, said at the time: "Warrior will continue to be at the heart of our combat capability for at least another 25 years with state-of-the-art firepower and electronics."
The Warrior armoured vehicles entered service in 1988 and "have proved a resounding success for Armoured Infantry battlegroups", according to the MoD website.
It adds: "The Warrior infantry fighting vehicle has the speed and performance to keep up with Challenger 2 main battle tanks over the most difficult terrain, and the firepower and armour to support infantry in the assault."
The website says they "provide excellent mobility, lethality and survivability for the infantry" and describes the Warrior as "a highly successful armoured fighting vehicle".
A Ministry of Defence spokeswoman said: "The focus of the £1 billion Warrior upgrade announced last year was to install a new 40mm cannon, add standard armour enhancements to allow for flexible detachable armour in the future and to extend the Warrior's life in service.
"They were not made in response to any identified deficiencies in Warrior's armour.
"Warrior has been upgraded throughout its service in Iraq and Afghanistan to tackle the threat from improvised explosive devices (IEDs) and mines.
"Warrior armour has defeated many IEDs and mines, protecting crews and the troops inside. Warrior provides some of the highest levels of protection available but sadly no armoured vehicle can provide absolute protection from the very largest explosions.
"Through state-of-the-art equipment, every effort is made to minimise risk on operations but it can never be removed entirely."
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