On the face of things, it might seem Matt Prior endured a modest first Test of the Investec Ashes series. England's wicketkeeper performed ably with the gloves, but he scored only 32 runs in the match.

But Prior's role extends far beyond batting and keeping. He is also the key man when England utilise the DRS in the field and as such played a huge role in their victory.

It is no exaggeration to state that use of the DRS split the sides at Trent Bridge. While Australia squandered their reviews in moments of over-excitement and emotion, England demonstrated a little more calm and utilised the reviews far more effectively.

It was not just luck that resulted in England, having retained both their reviews, using one of them to clinch the final wicket of the match. It was not just luck that resulted in Australia squandering theirs so that Stuart Broad, on 37, survived a thick edge that umpire Aleem Dar failed to spot. Broad went on to make 65 and, in partnership with Ian Bell, took the game beyond Australia.

The earlier decision to call for a review against Jonny Bairstow when the ball was clearly heading down the leg side suddenly appeared rather reckless. "If I had used my reviews better then I would have had an opportunity to use it when there was a howler like that," Michael Clarke admitted afterwards.

For Prior, the key to making good reviews is to take the emotion out of the moment. While he admits that there were times, when the system was first introduced, England employed it in a speculative fashion, they now have a formula which is proving far more effective. And, so much does England captain, Alastair Cook, trust Prior's judgement on the issue that he has never overruled him.

"The mentality of it is very important," Prior said. "The biggest thing is keeping the emotion out of it and just trying to make as measured a decision as possible with what you have seen.

"We have a process now where the bowler, myself and Cooky will have a chat about what we have all seen. Every now and then someone square of the wicket may have an opinion about how high did the ball hit on the pad when there's an lbw and we go from there basically. Cook hasn't overruled me yet, but never say never. It is a responsibility, yes, but you want to make sure you get them right.

"When it first came in, players thought this was great because they thought they could burgle a wicket here and there. 'Let's just review it because it might be out.' That's not actually the point. DRS is to make sure that if a mistake has been made you have an opportunity to right it. Once you look at it you realise that with a lot of the lbws the right decision has been given. It has to be a blatantly obvious one before you actually review it."

It is interesting to contrast Prior's attitude to that of his Australia counterpart Brad Haddin. While Haddin agreed that it was important to take the emotion out of the decision, he had a less sophisticated attitude to the process as a whole.

"There's no hidden tactic to DRS," Haddin said. "You go on feel. If you think you can use it, use it. If not, don't. It's not actually a big thing, the DRS."

Haddin may need to review that attitude, because it was one of the factors that cost Australia the first Test.

Despite a couple of setbacks, Prior remained adamant about the positive impact of DRS on the game. While he suggested one potential improvement - sides not losing a review if they had only been denied by an 'umpire's call' verdict on DRS - he also felt the general impact on the game was overwhelmingly positive.

It is worth reflecting for a moment on the possible outcomes had DRS not been in operation in this match. Would the Broad decision have been different? No. He was given not out by the on-field umpire. Would Brad Haddin have been given out to the last ball of the game? No. He was given not out by the on-field umpire. The DRS could not be blamed for either error. Even the dismissal of Jonathan Trott, perhaps the most contentious DRS moment of the Test, was more the result of human errors - both the TV umpire Marais Erasmus' error and that of the Hot Spot operator - than a failure in the system.

That Haddin decision might be the most pertinent. Had the DRS not been in operation, the match might have been decided by an error. Hot Spot and audio evidence showed an edge and Haddin later admitted he had hit it.

Still, Prior did concede that the margins between success and failure could be tiny. After suggesting England utilise a review for a leg-before decision against Phil Hughes in Australia's second innings, Prior admitted he had more than a few second thoughts before the TV umpire and Hawk-Eye eventually vindicated his judgement.

"When I first saw the replay without Hawk-Eye I turned to Cooky and said 'sorry mate'," he said. "It just shows how these margins are so small."

Prior also confirmed, despite rumours to the contrary, that he was fully fit. "I'm absolutely fine," he said. "My Achilles feels better than it has done for a long time."

He also added that he has faith in Steven Finn despite a disappointing display at Trent Bridge. "Everyone can have a bad day or a bad game," Prior said. "That happens. But we expect Finny to come back stronger than ever and come steaming in bowling with good speed like we see in training. We know how good Steve is and we know he'll be coming back fine."

While Finn was trusted to bowl only 10 of the 110.5 overs in Australia's second innings, his Test record at Lord's - his home ground with Middlesex - where he has taken 29 wickets in five Tests at an average of 20.65, will surely count in his favour when it comes to selection.

The groundsman, Mike Hunt, said he had been given no instructions from the England camp as to what type of wicket to prepare. Certainly the pitch at Lord's does not look as dry as that used at Trent Bridge but it will remain a bat-first wicket for whichever side wins the toss.

In an attempt to retain some moisture, the groundstaff have kept a layer of grass on the pitch, which may help bowlers in the first hour of the game but, with the sun baking the outfield and several used wickets on the square, the ball will run quickly to the boundary and reverse swing is likely to play a part.