For the record, as a European GCH (and/or SCH in the past or for my partner), I have never been refused assistance from the US number, which I have from when I was a US GCH/SCH previously. This tends to be open most hours outside the hours my normal service center would be open.

I would be most surprised to learn of a policy restricting GCH/SCH to use the reservation services of their resident countries only, particularly when downroute on a booking that has been disrupted.

I don't quite see why BA can't take a page from the book of other Airlines' elite programs, and actually provide their GCH/SCHs with a list of elite numbers in each country/region where they have one, and emphasize that as a GCH/SCH, you receive priority treatment anywhere in the world you travel with BA.

The current lack of clarity around GCH/SCH priority numbers makes it seem a bit more like BA only values a GCH's custom as long as he/she is sitting at home. With all do respect, that's not a good business decision for an airline, or any other merchant in a travel-related sector.