Ruud J.Lem was born in Nijmegen, the Netherlands. He was an engineer but came in 1978 with his wife Louisa and 2 young daughters to the United Kingdom.

In 1982 Ruud Lem and his cousin Wil F.Th.Lem started the research for the families Lem; Leme; Lems; and Lemm and published their findings in the big publication: Genealogia Lemniana (1993).

After a pause they continued with the search for the Flemish-Portuguese family connections of Martin Lem, the merchant with trade to and from Portugal in the 15th.C