easyJet do have a partition (no wardrobe) and 186Y seats on their A320s (177 on GATx), so it can be done with 29” pitch throughout.
There must be a trade off - a partition means less legroom throughout the cabin or fewer seats this higher fares or less profit. The GATx don’t have the spaceflex layout at the rear, like easyJet and the NEOs do. Perhaps in the future BA will shrink the galleys, install a partition and stick an extra row in the back, so LGW A320s could have 183 seats, so be careful what you wish for!