I thought the "British" in the original article was a hint, but does BA need a small plane?
Heathrow is short of slots and it would make sense for fewer short hall flights with bigger planes. They need the 320's and 321's so this is an extra type. They would be ideal for Cityflyer but the E. jets are reasonably young, when would they replace them? Would there be space in Gatwick for them or would BA return to the regions as they have now started some weekend flights? Most of the expanding airlines have many bases.