[i have also reported this elsewhere] what i am about to relay will probably be very mediocre to you but i am passing on details because it has left me completely flummoxed. i have a strong interest in aviation (including working for the imperial war museum, duxford as a young man) and i am also a lawyer by profession, so evidence is important to me. nothing in my fields of reference matches what i saw (apart from all the internet coverage of black triangles/tr3bs - although what i saw was a brilliant white in colour). also, over the years i have tended to be sceptical about stories of "chemtrails" but what i saw did not look to me like a normal contrail. yesterday afternoon (22 july 2018, around 3.00 pm, possibly between 3.00 and 4.00) i was in my garden with my wife when i looked up at the sky to see if there was any sign of the weather breaking. we have had extremely hot weather in the uk for quite some time now and there had been talk of rain at the weekend, but it hadn't materialised. i was basically looking to see if storm clouds were on the way. the sky was very clear, with just the faintest wisps of high cloud (alto cirrus) to the north. immediately overhead and to the south there was no cloud at all. as i looked up, i saw a white triangular shaped craft shoot from left to right overhead in a very broad arc. it was high up, i thought at least as high as the wispy-looking clouds, probably higher (difficult to tell because the craft did not cross the clouds from my perspective). without a doubt it was much faster than a commercial airliner. we are on the flightpath for gatwick airport and commercial airliners fly over us regularly. they are usually at 10-20,000 feet, they pass over us comparatively slowly and we normally hear a very faint noise from the jet engines. in contrast, this aircraft went from being first noticed immediately above my head to out of sight (last seen heading in a broadly east north east direction) in a matter of seconds. my first thought when i saw it was "that could be a tr3b, but how come it's leaving a trail?" as i understand it these aircraft are reported to have anti-gravity technology. i then took more notice of the trail itself and was struck by two things: 1. there was a very definite starting point, in the clear blue sky, as if something had been switched on. 2. it did not dissipate, it just sat there in the sky for some considerable time, just an arc shaped trail that was almost the same size at the 'start' point as it was immediately behind the craft. eventually the trail blew southwards and dissipated into clouds that appeared from the south west [possibly interesting that the weather changed to cloudy after this event]. my phone was indoors. the craft was gone so quickly that i did not have time to grab my phone and take a picture of it - and, perhaps stupidly, i did not take a picture of the trail alone because i did not think it would be of much interest to anyone. however i can state categorically that it did not dissipate like a 'normal' contrail, it was just a very long, arc-shaped trail with a fairly regular bubbling effect on each edge. the craft itself was white, not black, cloud-coloured in other words, but brighter - and it briefly appeared to reflect the sunlight. it was without doubt triangular shaped with rounded corners. it looked nothing like a commercial airliner. in fact an airliner passed slowly overhead and slightly more to the north a few minutes later, and from ground level is was readily identifiable as an airliner. the airliner seemed about twice the size of the triangular craft, but i think the triangular craft was at a much higher altitude. also, we could faintly hear the airliner's engines (there was no sound from the triangular craft at all). the only other point worth mentioning is that the triangular craft did not disappear from view in the sense that it could been seen fading away to a speck; it just sort of disappeared slightly sooner than i would have expected if it was just fading from view. it's hard to describe it any better than that. there were no flashes or anything, just one second it was there and speeding in an east north east direction, the next second it was gone and only the trail was left behind. there are many accounts of black triangles of course, but very few of white triangles. what i saw was definitely white. and the trail was very odd indeed. please also see attached sketch. i should add that i have curved the "contrail" in the other direction to how it appeared from the ground because i was focusing too much on illustrating the direction of travel that the craft took from my perspective. however the key points are that this trail had a very clear starting point, like something had been switched on, and it hardly changed shape at all between that starting point (above and to the left of me) and the last time i saw the craft (above and some distance to the right). it's a shame i can't draw in 3d, it would make this much easier!