Martin Brundle believes Mercedes lack a ‘natural speed’ at the Australian GP after he saw Lewis Hamilton put in ‘a lot of effort’ without a reward in qualifying on Saturday. The 39-year-old produced his joint-worst qualifying at any Australian GP with Hamilton only able to match his P11 from 2010. Mercedes teammate George Russell also struggled, as the 26-year-old had to settle for P7. The Silver Arrows even nearly saw both cars bow out in Q2. Russell could only manage the 10th-fastest lap in the second stage of qualifying. His lap time was also just 0.059 seconds faster than the 1:16.960 that…