onthemagicbeam,
It's not a case of replacing the SH fleet a LGW, more like moving everyone up to LHR after T5 is up and running. BA could then get rid of the B737 and close LGW. At the moment we're battling to crew the a/c we have without introducing any new ones. The shiny new jets will arrive once the B737 has gone and LGW has passed into history.