The title Count of Mértola (Conde de Mértola (Portuguese)) was granted to Frederick, 1st Duke of Schomberg by Afonso VI of Portugal, in 1663, as a reward for the Duke's service with the Portuguese Army.
The countship of Mértola was created with remainder to females, and since 1903 has been held by the Barons Fauconberg and Conyers.
Counts of Mértola (1663)
The heir presumptive is the present holder's nephew, Guy Armstrong (born 1996).
References
Count of Mértola Wikipedia(Text) CC BY-SA