the 35-year-old mclaren driver told the bbc he was ` chuffed to bits ' with his performance , but joked he was disappointed to finish behind former olympic rower james cracknell .
he added , ` there was such an amazing atmosphere out there .
` to come here and do a completely different sport with 36,000 other people ... it 's really cool , ' he said , before praising the collective spirit of the runners .