I have had WiFi on a couple of BA LH flights and it's been nothing special but functional.

Yesterday I flew MAN/LHR/ARN and somehow managed to get 2 A319s that were WiFi enabled (EUPR & EUOA). No mention onboard or anything and I only stumbled accross it trying to resolve a Netflix issue.

It was basically utterly rubbish, the MAN/LHR segment functioned but it was so slow it took the flight for two whatsapp messages to send. On the ARN sector it took the whole flight to get to the payment page and then it could not complete the transaction, other PX also commented on this.

They may as well not bother if that's the best they can do, no wonder they don't advertise it!