British Airways: same day upgrade?

It will obviously depend on the loading of business class for your particular flight.
You can make a note to check the seating chart every once in a while leading up
to your flight date.

If you really want it, I'd be checking for offers on the app prior to day of flight, and
then getting to the airport earlier than normal so you can either lock in or (maybe)
get higher on the wait list, although these days priority is generally based on airline
status, fare paid, etc.

Years ago, we were waiting to check in at Heathrow, behind only one woman. She mentioned that she hoped to get bumped up to a better seat, then proceeded to the counter. A couple of minutes later, and happy, she walked back past us, and said she’d got it.

I don’t know if it was Business or First class. I don’t know if she’d negotiated a deal, if she paid for it, used Avios points, simply asked nicely, or what. I just remember that she was wearing a faded denim outfit, jacket and jeans. Maybe she had clout, or a special strategy. We didn’t get any tips from her. Maybe wear jeans (which I don’t wear in Europe).

Last November (2023), I was flying from LHR back to PDX and I wanted to upgrade from Premium Economy to Business class. When I was checking in at T5, I let them know I was interested in an upgrade, if they had any Business class seats available. They sent me to a different counter, (to the left) and i asked the gentleman at the counter if they had any seats available and at what cost. He said if this flight was to any major cities like NY, LA or Chicago, it would be mighty unlikely and very costly. Luckily I don't Live in those cities. He found a couple of different seats in Business class and the cost was $250.00 or $280.00 USD. So yes, you can upgrade one class but it depends on which city you fly into, and if it's a popular city, it will be iffy and very costly. Good luck!

If you have the BA app you will usually be able to see an option to upgrade if there is availability. Sometimes you will be advised to speak to an agent at check in to enquire about availability. Both options involve payment to upgrade.

Over the last few years I've found business class on BA to be pretty full, particularly on intra Europe flights where there are fewer business class seats. On the occasions when I have been offered an opportunity to upgrade the price hasn't been too bad.

Complimentary upgrades are typically given to Executive Club members and staff and you usually only find out if you've been upgraded when you check in or your name is called out on the tannoy in the lounge. Rocking up to the check in desk wearing your finest and asking for a free upgrade just doesn't work anymore, there are enough people willing to pay and enough loyal Executive Club members who are first in line for an upgrade.