THE signs were there and could not be ignored. When we asked a clutch of wine merchants to describe their Christmas dinner drinking, several launched into the marathon with white port. Soothing! Delicious! Just the thing to prime the appetite! they chorused, with so much vigour that I put the theory to the test. Served well - chilled, Ferreira Extra Dry White Port (outlets above, £8.50 approx.) is indeed delicious and complex, developing from initial smoky, salted almond flavours to a rich nuttiness, then a firm, dry finish. Dryness is all a port labelled "dry" or "extra dry" will still taste sweeter than dry sherry. Straightforward white port is sweeter again and doesn't work - nearly the same magic.