BA 975 then UL 506 at Heathrow
Berlin → London → Colombo
Timetable, London time
13:05BA 975 from Berlin at the gate
12:35UL 506 to Colombo leaves the gate
23 h 30 apart on the timetable, overnight
UL 506 leaves 23 h 30 after BA 975 arrives on the timetable: more than half a day, so not a connection we count.