White object over Buckinghamshire UK.

It was about 10pm on a clear autumn evening, and I was looking out of my bedroom window smelling the fresh air, when I noticed an object approaching from my right.  It moved at a phenomenal speed. It moved from right to left in front of me. The object was a perfect cigar shape, exactly as if you were observing a saucer from an angle. The shape was pure, perfect and unbroken. The object was also a pure brilliant white.  There was absolutely no sound at all.  The weather was a clear still evening. The width of the object was approximately twice that of the moon.  I lost sight of the object as it was obscured by trees to my left.  The object travelled in a perfectly straight trajectory.  I do not believe that a natural phenomenon can produce an object of such a perfect shape and light, which travelled at such a fast speed in such a straight trajectory.  The sighting has utterly convinced me that there is life beyond this planet.