I would too, but it wasn't an option on this flight, which I only booked recently in the 50% redemption sale.

I'll keep an eye on MMB. Still that won't do much good if a baby appears because it missed a connection to the earlier LHR-CPT flight.

Don't get me wrong. I'm not losing any sleep over this (except perhaps on the plane, if I get bumped to a row with less legroom!). I like to get as good odds as possible for a good seat, but things can always go wrong- usually not when you're expecting it - and I don't worry about individual flights.