But don't forget to call him Sr. González-Cebrián rather than Sr. Tello!
I don't know if the Spanish surnames system is widely known by people in this board, but I'll try to explain.
As a preface, I suppose that you all know that women don't change their names when married, and that having more than one First Name is very common in Latin countries, like Spain, Portugal, France or Italy. So, we have
José María Aznar,
Pierpaolo Passolini, and
Jean-Paul Belmondo, for instance. Italians use to join both, French hyphenate them, and we simply put one after the other.
We all have two surnames, one being father's First Surname and the other being mother's. So, if my father is called Dad SurA SurB, and my mother is Mom SurC SurD, my name will be Myself SurA SurC. This is the full and official name but in everyday conversation we shorten it often, using only the First Name (or Names) and the First Surname. So we talk about José María Aznar, but his full name is José María Aznar López.
Doing some paperwork it is possible to officially join your two surnames in order to create a compound surname that works as if it were one. When joined, they are hyphenated, as it is the case of the media relations director of the Casa Real. This can be done for several reasons, but the most usual ones are a) the First Surname is too common and the person wants to be more 'special', b) the Second Surname is very rare and the person wants it to be transmitted to his/her descendants.
In the recent years (not more than 5-7) there was an amendment to the Surnames rule in order to guarantee the equality between men and women. When a couple have their first child, they can choose whether the father's surname goes in the first position, or the mother's. Whenever the decission is, they have to follow it for the rest of the children they have, to ensure all the siblings have the same surnames.
