Did the whole fuseboard trip, or just the lights ?? It should only trip the lights really, unless you have a fuseboard with an RCD and that is not a "Split load". IE, split in 2 sides, one for sockets, shower, cooker etc. The other side for lights. It just means that if your kettle goes faulty and trips the RCD, the lights will stay on.........Still with me.
Are the downlights low voltage (110v) or 240v ?? Most downlights are low voltage and don't have an earth at the lamp, so probably blew the trip on over current, more than 5/6amps. If they are working all right now then apart from the