As someone who would give you direct to GWC, I would not expect you to be FL270 at GIBSO, as it was no longer on your route.
What you'd get from me is the expect level at GWC of FL130 and a when ready down to FL270 to comply with the agreement between us and the next sector.
Direct to GWC is only really something that will happen if you're coming through first thing in the morning, ie arriving at GWC before 06.00z. After that it can become complicated with arrivals from the South and it all goes tits up for someone