silver glowing object watched for about 40 second

Staying at the holiday inn gloucester England at aprox 11.00 am on the 10/11.13 very clear sky next to no cloud,bright silver/white object watched for about 40 seconds,started to to turn reddish brown then gradually dissapear. Very strange. definitely not a plane.i believe the British goverment has its GCHQ situated nearby.it moved from right to left in a very straight line.silver/whiteish object could not see exact shape as it was sort of shimmering. no chance of balloon dead straight line didnt move up or down then just faded to reddish brown and gradually dissapeared.