If you have cancelled the mortgage for your property, it is important to inform the Land Registry about it.
If you cancel your mortgage with the bank but never inform the Land Registry, the mortgage will still be registered against the property for 20 years. If you decide to sell your property and the possible buyer requests a Note (Nota Simple) looking for the Land Registry information about your property, the buyer will find out that there is a mortgage against the property and he/she will not like that. Even if you tell the buyer that your mortgage is cancelled, he/she probably will not buy a property with a mortgage against it.
If you would like to sell your property free of charges it is important to clear the mortgage at the Land Registry.
So please, if you cancel your mortgage just send the mortgage cancellation Deeds to the Land Registry and ask to de-register it in order to avoid problems in the future. The easiest way of doing it will be asking the Notary (the one who was in charge of the Mortgage Cancellation Deeds) to de-register the mortgage in the Land Registry; the Notary will be in charge of all the paperwork and you will know that it is properly done.