Not long after this purchase, Manoel Pedro Guimaraens, a supporter of the liberal cause in the "war of the Two Brothers", was forced to flee Portugal hidden in an empty port wine cask. He settled in England, where is company remained based until 1927, when the headquarters of the firm returned to Portugal.

During this period, Fonseca grew rapidly in reputation and importance. By 1840, the firm had become the second largest shipper of Port Wine and in 1847 the first Fonseca Vintage port was shipped to England.

Since its foundation, successive generations of the Guimaraens family have upheld the Company's reputation. The founder's great-great-grandson, Bruce Duncan Guimaraens has recently retired but he supervised the Company's extensive vineyards in Upper Douro from 1955 - 1995. His son, David Guimaraens, currently acts as the winemaker and is responsible for the considerable stocks of ageing port wine in Vila Nova de Gaia.

Today, Fonseca occupies a leading position as a specialist producer of quality wood ports and as one of the top vintage houses.