The #cat has a microchip registered with #Identibase. After moving home I tried to update my address on Identibase, but they said that I needed to pay an annual subscription fee to do so...
My address is my personal data, and therefore comes under the #UKGDPR, so I submitted a Article 16 "right to rectification" request asking them to update the out of date personal data. Per Article 12(5) they have to do this for free.
And it worked! Identibase have updated my address for free.