Well, luckily I have a spare key that comes with my new boot lock. Today I tried to swap the lock barrels around so I could use the door key for the boot. Looking at it physically I couldn't work it out at all.

It appeared to me that these two dowels (arrowed) are holding them in.



To test this I hammered them out on the broken lock and sure enough, the barrel falls out easily.



Looking at the lock barrel it looks to me like at least one of the dowels is moulded into the barrel itself, making swapping these barrels almost impossible without attaching some kind of new dowel. The other thinner dowel that goes into the side is possibly removable but appears to be tapped into a hole making any ideas of disection almost impossible.

Conclusion: Don't bother approaching the car until you're prepared to don a new key or get creative with fiddly small metal pieces. I guess back in the day it was easy to get one ordered from the factory.

FFS, that looks like the petrol cap one, where you end up pretty much smashing the cap to get the barrel out...

Argh and humph if so

that tiny C-pin you mention is the only thing holding the barrel in. it even falls out sometimes so you can take the barrel with you when you open it

from what i can recall you can remove the pin with a tool, 2sec job if the whole assembly is off the boot

I'll try find some long nose pliers down the unit and have a go, thanks for the heads up