DiggerHawk
Registered
It is possible due to the way the pit lane works at Silverstone that a car can come in to the pits and gain positions or set a fastest lap.
This is caused by the pitlane short cutting the chicane at the end of the lap and the pitlane speed limit being too fast.
In this video you can see that the AI car was in fourth place before pitting on the last lap but ended up winning the race due to their pit box being after the finish line. Presumably this could happen in real life so the pit lane speed limit has to be set accordingly.
This example is using the International layout but I guess the same can be said for the GP layout.