The main compensation thread that I've found seems to be focused on EC/UK 261 so I thought I'd post this separately (Mods, please merge there or elsewhere if appropriate).

On a recent flight from LCA to LHR, Mrs Mileometer and I were on the same booking/reservation/PNR but when the boarding passes were created, I had access to Fast Track immigration and security but Mrs Mileometer did not (Gold + Bronze). Needless to say I didn't use Fast Track and "suffered" the utter mayhem that was LCA immigration and security that day, but I did send BA an email asking why this happened and, if this separation of privileges was intentional, what the point was. In under 24 hours I received a reply. Big apology, no explanation, and a £150 voucher.

To be honest, I didn't want a voucher (or Avios) from BA, I just wanted an assurance that this was a one off and that it wouldn't happen again because I travel through LCA quite frequently, but let this be a data point for anyone who finds themselves in a similar position.