I was driving home past foremark reservoir, near ticknall. along repton road. as i approached the reservoir main entrance, i noticed a bright orange light in the direction of the water itself. this was strange to me, as it almost looked like the sun, but the sun had set some time previously and it was dark at this point. i found a place to turn around and went back to the same place where, to my surprise, the orange light was still visible. i could not see the source of the light at this point, but it looked very much like rays of sunlight glowing through the trees. i parked my car in the lay-by that everyone uses to gain access to the reservoir and walked into the woodland, through to the car park of foremark reservoir itself. hovering directly above the small island in the middle of the reservoir was a bright orange ball. to the naked eye, it appeared to be the same size an egg. with my arm stretched out directly in front of me, and my fingers measuring the object, it appeared to be around 3-4 inches in circumference. the object was roughly 300-400 feet away from me at this time and was not making any noise or movement. i immediately took my mobile phone out of my pocket and tried to record a video of the light. at this point, my phone (huawei p30 pro) froze and i was unable to open the camera. after a few seconds, i tried again and received a message saying that my phone camera had overheated and was unusable. after another 30 seconds or so, 3 or 4 smaller orange orbs slowly floated out of the bottom of the larger orb and stayed perfectly still beneath it. they then began to move towards the water, coming to a stop about 6 to 8 feet above the surface. their glow was reflected by the water and they seemed to be lighting up the water beneath them. each orb flashed intermittently, which lit up the whole reservoir. after another minute or so, the smaller lights returned to the large light that was still airborne. in the time it took me to take three steps forwards, the larger orb had ascended some 100-150 feet into the air and then slowly moved to the south. it made no noise at all and moved in a perfectly straight line, without so much as a wobble or vibration. after a few seconds, this light then fell rapidly into the trees beneath. i could see the light shining through the treeline and casting shadows onto the car park. i walked around the outside of this woodland area, staying on the road that leads out of the reservoir and observed the light for a further 2 or 3 minutes. i tried to take some photos or videos again, but my phone camera still would not work. by the time i had put my phone back into my pocket and looked back at the trees, the light was gone completely. i rushed back to my car, as it was my intention to use my headlights to illuminate the treeline to search for an object or craft of some kind. when i tried to unlock my car, nothing happened. i pressed the button on my key numerous times and the car remained locked. after about 30 seconds of trying, the car unlocked and i was able to get inside. once i had turned on the engine, i noticed that my headlights were not working. i turned the dial next to my steering wheel multiple times and tried to turn on the high beams, but they remained off. i then had to turn the engine off and start the ignition a further three times in order for the lights to come on. once i got back to the woodland area where i had seen the orange light land, and shone my lights into the trees, i was not able to see anything at all. i walked into the woods, around 30 feet or so, but could not see anything and there was no sign of disturbance or recent activity. at this point, i left the reservoir and have not seen the light again since. please note: i have attached a file to this report. this was the only photograph that i managed to take, using my mobile phone, during the incident. i'm not sure why it looks the way it does. the photo should show a dark night sky with a small orange light visible, which is what i was looking at at the time of taking the photo. i am not sure how this image came to be, as my phone kept freezing when i was pressing the button to take a photo.