I don't think it's necessarily true. Milds are usually maltier and sweeter, with more caramel sweetness than bitters. Milds use less hops to accentuate the sweetness and most have a touch of roasty character.
The Boddingtons sound good but I'm not ready to go AG yet. My wife would kill me if I asked for more money for my obsession I mean hobby right now. I'm still looking for a extract Bitter recipe. So far I've found 2 that look interesting.