Wine maker James Godfrey presides over one of the world’s great treasuries of aged fortifeds. At Seppeltlsfield, in the Barossa Valley, he sits on an unbroken line of vintages stretching back to 1878. As well, he husbands countless multi-vintage fortified blends — making new wine, blending new with old, and deciding final blends for the market — everything from humble Mount Rufus Tawny to sublime Show specials like Seppeltsfield D.P. 90 Port to delicate Fino Sherries to blockbuster vintage ports.

Godfrey recalls being thrown in the deep end at Seppeltsfield, arriving as a qualified wine maker little experienced in the complexities of fortified wine making and blending.

Not that table-wine making is easy, but fortified production presents unique challenges. Few fortified wines come from a single vintage, single grape variety, or single vineyard as table wines so often do. And fortifieds require long wood ageing and blending of multiple components of different ages to achieve a consistent style from year to year.

Imagine being handed a glass of port blended from components, five to fifty years old, and being asked to continue the blend, starting with appropriate top ups this vintage. Sounds more like detective work than wine making.

Yet, in a nutshell, that’s what Godfrey does — makes hundreds of component wines each year, fortifies each with spirit, pops them in oak barrels, and nurses each one towards an outcome that might be five or fifty years in the future.

Blends of the past, of course, are the key to the future. And wine makers at Seppeltsfield work with a confusing palate of aromas and flavours, each a variation on the grape variety and its origin, the type of fortifying spirit used, and the type of oak along with where the oak sits and how long a wine stays in it. These are just the basic components which lend themselves to endless combinations through the blending process.

A typical Seppeltsfield port might contain wine made from six grape varieties, each with its own aroma, flavour, and ageing characteristics: white muscadelle and red grenache, mourvedre (mataro), cabernet sauvignon, touriga, and shiraz. Sourcing any of those varieties from more than one region further compounds the blend.

Muscadelle ages quickly, tastes neutral and soft, and, thus, makes a great equaliser for bigger wines. Grenache, especially from Seppeltsfield’s very old, low-yielding vines, ages reasonably well, and adds a spicy aromatic edge and a full, fruity palate. Mataro, mainly from the Barossa, ages rapidly, and adds sweetness to a blend. Godfrey calls it the ‘merlot of fortified’. Shiraz ages forever and adds terrific robust flavours that easily match quite strong spirit flavours. Because it takes so long to age, it plays only a small role in young tawnies but gives the backbone to the older ones. Cabernet sauvignon adds a distinctive fruit character as a minor component in blends. It ages well and it seems that no matter what spirit is used to fortify it, the fruit flavour always wins in the end.

Fortifying spirit, added in sufficient quantity to a fermenting wine, brings the ferment to an abrupt halt and adds another flavour to mingle with grapiness and sweetness of any unfermented sugars.

Like grape varieties, spirits come in many flavours and become part of the aroma/flavour palate used by wine makers. Godfrey works closely with Barossa distiller, Tarac, to get exactly the styles he needs for each grape variety.

Flavours range through the clean, light, neutrality of marc spirit (made from grape skin and seeds), to floral grenache-based spirit, to oily/fatty, wine-based low-strength spirit, to the ‘over the top’ styles used to fortify vintage port.

And although most fortified wine is aged in old barrels to avoid the overt oak flavours that are desirable in many table wines, the type of oak, its size, and where it is stored exercises a profound influence on wine flavour, especially over long periods of time.

Godfrey experiments with this flavour aspect, too. In one such test, he filled three barrels of the same oak with new fortified wine in 1987 — a 480 litre puncheon, a 280 litre hogshead, and a 180 litre quartercask. These were stacked at the highest, hottest level in one shed. A second hogshead was filled with the same wine and placed in cool storage. Making a long story short, by 1995 when I tasted samples from each cask, significant aroma and flavour differences had emerged,

The elements described so simply here are what the wine maker sees on day one. Time and blending alters the flavour palate immeasurably. And when we finally drink a D.P. 90 Port, or its like, we smell and taste the fruits of perhaps fifty years’ labour.