I don't think you would get away with that in the UK since the CAA have insisted (rightly IMO) that holding fuel is added to trip. Then 'contingency' is added.
BOAC, for clarification, do you mean 'holding fuel' at
destination? It is my understanding that legal minimum alternate fuel from dest to altn includes only go-around, climb, cruise, descent, 30 min holding at 1500 ft agl and an approach, but does
not include any contingency.