That is to say a wealth tax on overseas property owned by folks ordinarily resident in the UK for tax purposes - another can of worms all together.

You will have noticed that when leaving the UK, your passport is scanned and upon your return it is scanned again. There is more to that than meets the eye more than terrorism prevention - it's HM Revenue & Customs after all and departments are beginning to talk to one another - perish the thought - whereas Spain just waves you through!!