It was around 6.30 pm, dark and i was travelling as a passenger in a car from windsor towards maidenhead. i saw aircraft lights on my left, which were decending at around 1500ft, landing west-east at heathrow. i looked again and saw what i thought was another plane with flashing lights however this craft was closer to me, much lower and travelling east-west. i observed the craft which flew across the fields in my direction and then banked left to fly parallel with the road i was travelling along, directly left of me. the car was travelling at around 50mph and was moving alongside the craft for quite some time. at one point the craft was so close i could see its shape was triangular, with bright white lights at each point. i could see that the craft seemed to have a dome underneath its centre, i noticed what looked like gold coloured foil around a domed part underneath that glowed slightly. i also recall that the craft seemed not to be flying flat but leaning slightly to the left for some time. i couldn't make out much at he top of the craft i remember that there were red and blue flashing lights around the base of the circular centre exactly like the strobing lights on an airplane. i recall there seemed to be more blue lighting more than red. the craft seemed solid and slightly reflected the glow from roadlights. it seemed to be a matt grey. i tried to take some pictures through the side window with my mobile phone but my view at this point was partially obscured by trees & bushes and reflections on the glass, although you can see a grey triangle with a white corner in all the bluriness. the craft continued in the same general direction but further from the road, where i struggled to keep my eyes on its movement due to the houses that lined this stretch of the road. the craft was flying low on the other side of the houses. when i could see the craft it was moving between the houses. i lost sight of the craft and continued home which was only a minute away. i exited the car and scanned the sky to see if i could see it again, it was then i saw it, this time travelling back towards windsor. it was crossing in front of me, very close and very low. i was standing in the centre of my car park and it was directly in front of me at around 80 degrees from the horizon. as i went to take photos the craft turned into an orb of light, the orb seemed to be smaller than when it was in its triangle state. one photo shows the craft in this orb state. my phone didn't seem to want to work very well and it seemed frozen when trying to take the shots. when i next looked up the craft had changed back to the triangle shape. it took a long time to actually get the shots, the ones that i did get were very shaky apart from one showing the orb. the craft was silent and very dark this time, although i could see the blue & red flashing lights, there was no sign of the glow underneath as i had seen earlier. i could still make out the triangular shape of the craft. it moved onwards very slowly and continued flat and straight into the distance until i lost sight of it. as it moved away i could see two white lights at the rear. as shown on the photos submitted. i though i saw it a minute or two later in the distance but it could have been an airliner