When I was a kid only MAN GLA and EDI used SHT, Belfast had stopped.

Aberdeen, Newcastle etc all were Speedbird, albeit alphanumeric. Then around 2008 ish I guess all UK domestic changed to Shuttle, including the LGW services. The last of course to change was Jersey in October 2023. There had also previously been LBA and NQY.

Aldergrove used 4/5 during the shuttle days, so it was nice for BHD to return to 4/5 a year or two ago.

As for why MAN is 2/3, I'm not sure.