BA are thankfully like VS in that when you order a VLML that is exactly what you get and not a Vegan VGML like you get on the US carriers. On the US carriers I don't bother anymore and just eat the meat free bits of the standard meal - much "tastier".

As an aside can't say I've ever had a problem obtaining a veggie meal on BA without ordering. I tend not to order one now as I heard it impacts upgrade chances. Not sure if this is true but I sure as hell haven't been upgraded when not ordering a special meal!