With respect to everyone who has commented so far< I think you give too much credit to BA and LGW having a 'master plan' for gate allocation. I think it is a bit more random.....there may be a plan at the beginning of the day but delays and other ops considerations mean it gets more random through the day. Albeit I dont fly in and out of LGW as often as LHR or LCY, on recent occasions I have left and arrived from Pier 3 and also landed (quite late) into the closest gate to the terminal on the main Pier....and left from half way down Pier 2....all short haul destinations. None of the distances are particularly long. Compare them to LGW North on the far pier, or Terminal 4 all the way along the extension on the east side beyond the main building.