Singapore and the UK have had longstanding bilateral issues. It is a really long and complicated issue, so here is the basic gist. SIA has had to fight tooth and nail to obtain more traffic rights into the UK, and they also want transatlantic rights out of LHR
. Each time S'pore and the UK meet to discuss the bilateral, the UK gives S'pore a little bit more, but not everything they want. SIA therefore uses up all available rights as soon as they are made available (and as soon as the slots are available) in order to tell the UK "hey we have used up all our rights, we carry huge amounts of pax and cargo, let's negotiate again". Basically it is a tactic to get the UK authorities to talk and gain more rights, with the ultimate aim of transatlantic rights.
As for MAN
, the traffic is mostly low-yielding tourist and VFR traffic. The flights are not terribly profitable. I am, however, surprised by the 92% pax load factor in the middle of April!
By the way, the UK has granted 3rd/4th freedom rights to fly on to the US, but that isn't sustainable because SIA can't pick up passengers between the US and UK. BA
, by contrast, has huge unutilized rights out of SIN
, including the right to base up to 20 747-size aircraft in SIN
As far as the bilateral goes, Singapore is in a weak position because their negotiators gave away too much too early, and they have little left to offer that could be of use to BA
Like I said this is a long and complicated issue and I have only just scratched the surface of it.