A lot of the Scottish services do have a BA code (when connecting onto a BA flight). IOM-LHR, SOU-NCL, SOU-EDI, SOU-GLA all have BA codeshares (as did MAN-GLA I think) but MME-LHR doesn't (although it is still early days). I guess it depends if BA feels that LDY is a threat to their BHD route and if MME is a threat to NCL? However, LM have got the LHR slots from somewhere and in the grand scheme of things, LM are not going to take much away from BA.