The filtered wine has the advantage of being ready to drink without decanting and is usually bottled in a stoppered bottle that can be easily resealed. However, many wine experts feel that this convenience comes at a price and believe that the filtration process strips out much of the character of the wine.
The accidental origin of late bottled vintage has led to more than one company claiming its invention. The earliest known reference to a style of port with this name in a merchant's list is to be found in The Wine Society's catalogue from the spring of 1964; which includes Fonseca's Quinta Milieu 1958, bottled in the UK, also in 1964.
Unfiltered wines are mostly bottled with conventional driven corks and need to be decanted. After decanting they should be consumed within a few days. Recent bottlings are identified by the label wording "unfiltered" or "bottle matured" or both. Before the 2002 regulations, this style was often marketed as '"traditional", a description that is no longer permitted.
LBV is intended to provide some of the experience of drinking a vintage port but without the need for lengthy bottle ageing. To a limited extent it succeeds, as the extra years of oxidative ageing in barrel does mature the wine more quickly.
Typically ready to drink when released, LBV ports are the product of a single year's harvest and tend to be lighter bodied than a vintage port. Filtered LBVs can improve with age, but only to a limited degree; whereas the unfiltered wines will usually be improved by extra years in the bottle. Since 2002, bottles that carry the words "bottle matured" must have enjoyed at least three years of bottle maturation before release.