We've just flown flights that I'd booked using Barclays vouchers to 'upgrade' PE to J. In MMB it said no upgrades possible, as expected. However, 1 hour before OLCI opened, or at least that's when I noticed, it came up with a POUG. I clicked through and it showed as not possible for the outbound, but available as c.£700 pp for the inbound. Given the inbound was the BAH-LHR 1.55am and we had 5K/6K (i.e. Club Suites mini cabin), I didn't take it any further.

I was under the impression that Avios bookings couldn't be upgraded using cash. Am I wrong or was this just BA IT doing its thing?