Simple fact is that BA have no new long haul aircraft on order,- ever. All recent fleet investment has been on the programme of replacing 737/757s with Airbuses on their marginal European routes. They there therefore unable to operate to any additional long haul destinations or raise frequencies without withdrawing others. The only solution appears to be to move remaining 767s from short haul to long haul and take back the 767s leased to Qantas, but the economics of 767s on most of their routes arent great.
The shame is that this leaves the way for their competitors, UK and foreign, to erode their long haul market share and route structure. Already their own route coverage in the Far East is half what it was ten years ago ( although the Far Eastern economies are back growing strongly) and other areas look threatened if they want to expand in India or USA. Competitors must be licking their lips.