I doubt Google got much from me, I sent back the hard copy form by post.
And no, I didn't use the code to go online and request the form.
I got the letter - only, it was addressed to a house two doors down (so I did the Postman's job and delivered it to the correct address).
Never received the original letter to my address (presumably it went somewhere).
Got visited by Census ONS lady, got given form. Completed and returned by post.
At which point, I would gloat about the superior security of old-style hard copies only in protecting personal data.
Apart from the fact that I've now had three further visits from the ONS people saying they have no record of me completing the census, the last one being ~2 weeks after I returned the form.
Still, if Royal Mail can lose both the inbound letter and my return, that's a form of security, right?