Stroud Glos. They have just been round sprayed water to no avail. Leaks through light socket so no way to tell where the water is coming from. Next, they want to cut a section of the ceiling to check water path. 🙁 Heavy rain sometimes nothing, light rain it comes through also few inches of snow melting it came though.
My guess, and I am no builder is that a few hairline cracks could be the culprit. Hate flat roofs