[QUOTE=Iamnotlost;31072995]
I can also try asking nicely at check-in but I suspect that won't get me very far.
/QUOTE]
Unfortunately, it won't.
Originally Posted by
Iamnotlost
Though I've just reminded myself that I arrive at T3 on AA - presumably that won't help with trying to retrieve my checked bag??
Nope, it just means that once you eventually manage retrieving the bag you'll have to schlep it landside to T5.
And to be honest, once you have retrieved the bag anyway, there is little point in going to INV for a back to back. If you plan on pushing to get it back, you might as well just take the bag and leave.
Really though, those things are best achieved HBO. Have you considered sending your bag separately as freight? It's often not very expensive, may well fly on the same plane as you and you can then get off in London much more easily having conceivably paid less than the INV-LHR flight would cost you.