I walk this road daily while walking my dogs, sometimes straight up from where the distant shot was taken from, and other times emerging from the side road where the accident begun.
So let's hypothesise how all this happened shall we... Here is my take on it.
The Saab enters from the bottom of Kemble Road, picking up speed as it travels up the road. This road is a rat run, and the poor traffic calming just encourage it really. As the Saab approaches Loxton Road, about 75 metres up on its right, a Mini begins to emerge. I can only assume at this point there was a misjudgement of intention and speed, and the Mini is now 45 degrees into the path of the Saab.
The first impact occurs Saab offside front to Mini nearside door, punching the Mini off to the right, and causing the Saab to veer to the left (more than it already may be doing for evasive action.
As the Saab moves left it now makes a second impact with a parked Fiesta, this time Saab nearside front to Fiesta offside door. This impact heavier that that to the Mini, joins the cars together for a moment, causing the Saab to drag the Fiesta up the road a little causing the Fiesta's frontal impact with the tree. This impact frees the cars once again and the Saab now missing its nearside drive components, grinds to a halt.
Meanwhile on the other side of the road the Mini comes to rest quite firmly in the rear end of the 4th vehicle involved, this time a parked Micra.
My biggest worry is I know people who live on this junction, and I quite frequently stand and chat on the adjacent pavements. The sheer scattering of cars and debris could have caused nasty injuries to passing pedestrians.
The next concern is speed. I would say I'm not pointing fingers here, but the fact is I AM! Given the speed limit on the road, and the position of the cars post-accident, I would have to say the manner the Saab was driven is was almost reckless. Travelling @ 20mph, the impact with the Mini alone would have been almost enough to stop the Saab in its tracks. The fact it managed to punt the Mini so hard, and so far out of its way suggests there was either no time to react, or there was speed involved..
But that's not all. Not only was there such a violent punt, but then the Saab managed to carry enough speed (one would assume now under braking) that it struck a parked car further up the road. Again, under normal circumstances I would expect the second impact with a this time stationary object to end the motion of the car. However once again it doesn't. The impact is violent enough to embed the Saab in the Fiesta, transfer motion into the stationary and one would assume secured Fiesta. So much energy transfer that it managed to propel the Fiesta at a great enough speed into a nearby tree to cause extensive damage to the front of the vehicle.
NOW... The Saab is STILL carrying enough inertia to keep going still, separating from the Fiesta and continuing another car length before finally coming to rest. Assuming throughout this accident a reasonable reaction was made to try and stop the vehicle, the distance travelled and damage caused is quite astounding.
So, people of Forest Hill, and those who travel through it or to it for work.... Slow down eh!
I'm not for one second here saying the Mini didn't fail to look left, and pulled straight into the path of the Saab, causing an immediate, heavy impact. But I would say the damage from the subsequent impacts indicate the Saab was doing more than the posted 20. Maybe its time that Kemble Road was furnished with full length speed humps.?
OK, so just for a little clarification of the start and finish positions of the vehicles were, here is a little diagram.
Arrows are starting points of cars, rectangles end points. Stars are impacts (pink 1st, red 2nd.) Colours of symbols refer to the colour of the vehicle.
Hopefully this demonstrates the distance travelled by the Saab in total, and the road layout and markings.