Looks like everyone is getting a year added to whatever their current card expiry date is... which is exactly what the BA e-mail said would happen.
"We've added 12 months extra onto your Silver Executive Club membership."
I thought it was pretty simple when I first read it
Still think it's a nice gesture, despite the "oh but she got 7 months more than me" / "but I already qualified for next year so I want another year on top" whining on here. The alternative was getting nothing and we got a year extra plus discounted TPs. It's still a win!