So because the BA Shuttle carries little point to point it's bad even though it offers hundreds of options to the travelling public? OK....
BTW I am Scottish so as being of the North goes, kinda beat you on that one, if this was a competition, which it's not.
One key point on IAG. The subsidiaries are better described as OpCos (operating companies) rather than "brands". Key strategic decisions for Aer Lingus are made in Dublin as is fleet strategy, it remains an Irish company. It also licences it's own brand with the independent company Stobart Air. Fleet planning is made in Dublin but subject to CAPEX approval by IAG and they're expected to align with the wider group policy, hence A350s can swap from Aer Lingus to Iberia before delivery as that benefits both OpCos. Likewise BA licences their own brand to ComAir and SunAir but neither have ownership links with IAG
As for the BA Shuttle competing with Iberia to Madrid and Finnnair to Helsinki, well Iberia is a JV partner and Finnair is a Oneworld partner so they're not competing in the way you mean. The Finnair / Iberia option is once daily subject to availability and doesn't connect to all long haul options at HEL or MAD. Hence the only available option may be MAN-LHR-HEL/MAD-xyz depending on where you are heading to. It's sub par to make two connections but the point to point market for a legacy out of MAN to HEL/MAD isn't strong enough given most of the point to point will go easyJet or similar at way less cost. The market HAS moved in the direction of point to point away from hub and spoke in Europe but to the detriment of the legacies who provide the connections MAN asipres to for the wider world. It's a tricky circle to square.