diamond shaped craft with coloured lights underneath.i was riding my motorcycle heading north on the A46 between coventry and warwick at approx 21.30 hrs,when a quarter of a mile in front of me i saw a huge grey colored diamond shaped craft in the sky.the craft was moving west to east and was approx 200/300 feet above me when i passed below it.although it was dusk, visability was good and my view was clear and for a few moments i saw underneath the craft;it had 13 lights,2 red, which were located at two ends of the shape[these were flashing on and off],next to each red were a single white light and then a further 3 white lights in a line,next to these were 3 green lights in a line[these started from the other ends of the shape]. i would describe the colour of the craft as matt grey and looking industrial[if thats the word],and i could not tell if it made a noise due to the sound of my engine. i would guess the size of it was about the same as ten football pitches put together and it took about 15 seconds to move across the dual cariageway,i was still observing it over my shoulder as i rode away.((NUFORC Note: Date is approximate. PD))