Did they collect the APD from you? From my reading in the other thread, they're not equipped to do this.
Not physically collected at the gate, but my credit card was already on file from when the request was originally made.
The SWU was pulled so it was not an op-up.
On that particular day I queried the upgrade while checking in and at the FL but it had not cleared. Checked again at the gate and still not cleared, but literally moments before boarding started it cleared.
Now if there had been no previous request until reaching the gate then I can see the problem, but that is not unique to LHR as I've seen staff at ORD doing everything possible to avoid processing a SWU upgrade request actually at the gate.