Of the four sons of Hermanus Koekkoek Sr, the oldest, Hermanus Jr, followed in the footsteps of his father, and with that of his grandfather. As usual in the Koekkoek family, he learned the trade from his father. After that he painted romantic seascapes with ships for at least twenty years, both in wild and calm water. The painter seems to have a great preference for a strong breeze in which the ships can barely keep course on turbulent waves. Like his father and grandfather, he sold a lot of work in England and this is probably why he was regularly found in London from the 1960s. In 1869 Hermanus jr moved permanently to this city, where he started an art trade and developed into one of the leading traders of his time. He mainly sold romantic paintings: masterpieces by his father Hermanus, his brother Barend Cornelis, his cousin Willem and his own navies. It is also known that he traded work by, for example, the landscape painter W. de Haas Hemken, by J.M.H. ten Kate and in the mid-seventies also the expensive and beloved cityscape painter Cornelis Springer. In this English period, the painter's work shows similarities with that of the Hague School painters, in particular by Jacob Maris, due to the looser touch and attention to a more atmospheric depiction of the Dutch landscape. His subjects then expand with Dutch beach scenes with bombs that are geared to the English market, cities on the water under high cloudy skies and ships off the English coast. He usually signs his paintings with 'J. van Couver'.