The ANU-SKB sector normally has 90-120 pax on average. LIAT's largest aircraft has 50 seats and Winair's 19 seats. Simply they son't have the capacity to transport that many pax in one go.
BAladdy - my anecdotal evidence was that it was fewer than that, but I am glad it is more. In which case, would it make more sense to operate weekly LGW-SKB-LGW in a 767? Hypothetically of course - there are plenty of other thin Caribbean routes which have stopovers, but
afaik, 777s are now the only LH BA equipment at LGW?
I'm not sure how important cargo is on these routes - maybe some mail but the important stuff goes with Fedex. There is little agricultural produce on SKB / ANU - St Lucia grows a lot of 'fair trade' bananas, but I'd guess these are shipped by, well ship! The only other, err, high value cargo round there isn't the sort you'd take through airport scanners! Plenty of food, soft drinks etc come into both SKB and NEV from SJU, but that's not BA's concern.