From what I understand, the main thing to note is that, if declared on insurance, you are expected to lock your bike wherever & whenever you stop.
Say you take a casual ride on a Sunday stopping a couple of times for a cuppa. The insurance company will expect you to carry your big heavy chain with you and lock it up each time you leave the bike unattended.
No doubt but you can be sure they'll ask if you had it locked up. If you say yes, I'd imagine they'll ask why you didn't tell them.How are they going to know? I'm pretty sure there's no legal way to use making something more secure as a way to wriggle out of not paying