Traffic lights on chiswick round about

As you approach the roundabout from the a4 (direction towards central london), you hit the the main traffic lights. A second set of traffic lights can be seen ahead of you, which are meant for the traffic going around the roundabout(to your right). On 3 occasions I have seen cars leave the first set of lights on red, as the second set turn green and they believe that is their signal to go. I believe a slanted cover to obscure the view on the second set of lights may help. I have seen cars nearly get hit as a result, so this is a safety issue.