I'm not sure why some people think slots are an issue for BA regarding reasonable levels of long haul expansion.
Each long haul flight obviously would only need one slot pair assuming it runs daily (and many new routes would start at lower frequency than that)
Whats MAN running at frequency wise now - 10 or 11 a day? Cut that to 7 or 8 like it often was pre BMI merger.
Cancel the 3* slotsitter that is LBA
Cancel the 3* slot sitter that is RTM
Stop messing around with Palma and Ibiza etc.
You've just created 9 or 10 slot pairs.
OK, they might not all be ideally timed for long haul, but thats for the schedulers to sort out!
The reality is that it is likely to take BA 3 years+ to launch that amount of new long haul routes..............