‘Unregistered’ with regards to a land registry search in the UK simply means that the land is not registered with HM Land Registry (in England and Wales) or Registers of Scotland (in Scotland) or the N.Ireland Land Registry (in N.Ireland).
It does not mean that the land is not owned by anyone, and it does not mean that the address is not valid. It simply means that the relevant land registry (which we will simply refer to as the ‘Land Registry’ from hereon) holds no information or deeds in relation to the land.
Title deeds relating to land that is unregistered will be held privately by the owner or their mortgage company, as opposed to the Land Registry who maintain title deeds in respect of registered land. There is no quick or simple way to locate the owner of a piece of unregistered land; and there is no way to compel an owner of unregistered land to show you their deeds without a court order. Put simply, dealing with unregistered land that you do not own can be very difficult.
Thankfully, registration of land is now compulsory on sale and certain other dealings, so the vast majority of land in the UK is registered with the Land Registry and it is very easy to prove ownership.