Thomson Airways already operate long-haul, but only 3 or 4 departures each winter for the fly cruise pax. Monarch and Thomas Cook A330's also operate to New York, Barbados and other caribbean destinations for the fly cruise crowd (and short-break shopping trips) of Bath Travel/Kuoni/P&O. In total around 1 flight every fort-night from BOH in the winter months is a long-haul flight. So plenty room for improvement and additional capacity (once the economy kicks back into shape)
Barbados could definitely be operated weekly from BOH - Bath Travel tried back in 2003, but they were doing so with a B747-200 (440 seats) and that proved too much capacity... A330 or B787 would be ideal.