From back garden whilst out with dog...Observed bright white object west of my location about 40 degrees above horizon - thought was aircraft with headlights on, and watched as it tracked east on slow ascent path...But into end that white light was pulsing...No red or green aircraft lights visible... after a minute or so it disappeared in high light cloud and was obscured, but followed path by eye through cloud, until it reappeared still on easterly path... also aircraft at this time, as normal, whit lights and red flashing beacon in same vicinity but appeared lower... maintained observation of light, which was it clearly pulsating / almost flashing on/off...Only bright white light, no coloured navigation lights where observed... then to my amazement it appeared to simply stop and maintained a stationary position for maybe 5 seconds then took off again at 90 degrees to its original path, heading south... i observed it for about another 30 seconds to a minute as it went away from me and disappeared behind a large cloud. i regularly observe aircraft in this area in the skies at night, as we are close to flight paths, i have also observed chinese lanterns in the sky (wind blown) and frequently see helicopters, both civilian (police mainly) and military (not often) and rochester has a small airfield, but does not fly at night. i have also observed satellites at night (directly overhead) and usually in a north west of south east orbit, but i have never observed anything similar to the observation i am reporting. i would interested in finding out if anyone else observed this 'light' this evening... i found this observation most peculiar - my thoughts were, what the hell is that? i came to the conclusion it could not be a drone copter as it was too high and must have travelled a fair number of miles during my observation...Not possible for a remote control drone copter as range of radio control would be an issue... i also noticed no sound, although i could clearly hear the aircraft observed during this period, the pilots of which i would suggest must have also observed this light their aircraft was flying west/south west to east/north east... unfortunately i do not have any digital or photographic evidence...I was too engrossed in watching it...