LONDON, England - Lewis Hamilton's home win at Silverstone was proof of his mental strength and a big boost to his Formula 1 title battle with team mate Nico Rosberg.At least according to Mercedes motorsport head Toto Wolff.The win cut the gap between Hamilton and leader Rosberg to four points and came after some were questioning Hamilton's mental strength and judgement after he made a silly error in qualifying on Saturday (July 5).'HEAD SEEMS TO HAVE GONE'Retired triple champion Jackie Stewart, whose tally of 27 wins Hamilton equalled on Sunday (July 6), said on July 5 2014 that the Mercedes driver was hugely talented but "his head certainly seems to have gone a bit".Wolff said that was not at all the case: "I think, different to what the perception, that he is mentally very strong and he can cope well with having had problems."One of the examples (in the race) was we had another pit-stop which wasn't perfect on the left rear. The first thing he (Hamilton) did, he came on the radio and he said: 'Guys, don't worry. Let's make the next one better'."He would have moved himself out of that low (point) anyway but winning at home, winning in front of such a crowd... that's going to give him a big boost."Wolff said both his drivers reacted calmly to their situations on July 6, a change from some of the heated pit-radio conversations heard earlier in the season when they fought wheel-to-wheel.NO NEGATIVE EMOTION"There is no negatively excited emotion. Everything goes very calm. It was the same for Nico. He was facing disaster and retirement and he was very calm and trying to go through the settings," he explained. "It was the same with Lewis, the way he communicates with his engineers is 10 out of 10."Rosberg, who had led the Drivers' standings by 29 points, had his first retirement of the 2014 season at Silverstone.Hamilton, Wolff said, had been focused before the race after the blow of qualifying, when he aborted his last lap under the assumption that his time could not be improved - only for Rosberg and others to go quicker because of changed track conditions."We spend a lot of time with each other and...he (Hamilton) has a very stable, mature way of tackling things."