Indeed Stravinsky, if you do not have an address to use in the UK you would be right. I have to suggest though, that there are few if any british ex-pats in Spain without a UK address they could use. It does not have to be your primary place of residence, just an address through which the DVLA or anyone else regarding your licence can contact you. A more serious concern for me is if I did swap my UK licence to a Spanish one, I would lose entitlement to drive certain vehicle categories which I have by default having held my UK licence for over 40 years. On a recent holiday in the Carribean I also found that the particular car hire company accepted my UK licence but would not have accepted a Spanish one.